Character Gallery Relationships
Oh, I don't know. I just don't know what I am, what my value is.

X is a mathematics variable and the co-host of Battle for BFB, (formerly the host when Four was gone).

X's first appearance in BFB was in "Getting Teardrop to Talk" where he and Four lead a game to win "a BFDI" (which means the winner will get another Battle for Dream Island). X appeared alongside Four, another abstract being representing a real-life number or variable.


X is simply a drawing of the letter X with a yellow body and lighter yellow limbs. Similar to Four, he is purposefully drawn simplistically, with different assets and four fingers.



X seems to be much more friendly than his partner Four, and is usually seen to be quite happy and friendly towards almost every contestant. However, X also seems to be quite soft, as he cries after Four stated that nobody noticed his disappearance (despite Cloudy asking about X), and became frightened after Four screeched at him and when Snowball threatened him in "This Episode Is About Basketball". He can also be considered a bit ignorant, such as thanking the ground for "catching" Beep after they fell from their plane, or even asking to get screeched by Four. He also shows to get very nervous under pressure. As he hosts in "This Episode Is About Basketball", he's very hesitant while talking and tends to mess up things, such as reading the votes backward when Free Food was up for elimination. X is overall quite docile by nature and remains loyal to Four, even after the times Four has mistreated him.

However in "A Taste of Space", he shows off a more irritable, somewhat bratty side to his character as he begins subtracting points from the teams for petty and minor reasons.


  • Levitation: As shown in "Getting Teardrop to Talk" and "Fortunate Ben", X has the ability to float in mid-air. In "Get to the Top in 500 Steps", he levitated to the top of the viewer's screen. In The Four is Lava, he floats right above Four. Both Four and X have to idly stare at the viewers for the ability to work.
  • Teleportation: He can also seemingly teleport, as he got back up to his platform after being knocked back by one of his baskets in "Getting Teardrop to Talk" and teleported to Firey and Four in "Who Stole Donut's Diary?".
  • Construction: He can also build quickly, as he built the challenge station for "This Episode Is About Basketball" in 3 seconds (3:26 - 3:29).
  • Regeneration: In "Enter the Exit", X was shown to heal his leg almost immediately after Pie dislocated it to make a four. It also seems that he can reattach entire limbs with nothing but bandages in "Fortunate Ben".
  • Pain resistance: When Pie dislocated his leg, he took it with no more than an "Ow!".
  • Shape-shifting: As shown in "What Do You Think of Roleplay?", both X and Four can shape-shift, or change their physical appearance.
  • Heat resistance: As shown in "Return of the Rocket Ship", X was able to survive in molten magma/molten iron, and in "How Loe Can You Grow?", X was able to stay alive when being sunburned.
  • G-force resistance: X was able to remain stable even after being flung towards Earth's core at 2,763 miles per hour (4,446 kilometers per hour) in "Return of the Rocket Ship".
  • Strength: X broke through the earth's crust with no tools or assistance in "Return of the Rocket Ship".
  • Telekinesis: When X snaps his fingers, he can make things float.


  • Burn tendency: In "How Loe Can You Grow?", X is shown burning because the sun is closer to earth. However, other characters (except Firey) were not burning.


X plays a role as Four's assistant.

He sets up some of the challenges, as seen in "Getting Teardrop to Talk", where the contestants must reach X to bring his baskets back, and in "Fortunate Ben", in which the contestants must keep their respective teams' plane in the air as long as possible. X is the person who hands out prizes to the safe competitors at Cake at Stake.

He hosts Cake at Stake and sets up the challenge in "This Episode Is About Basketball" as a temporary replacement for Four.

As of "The Escape From Four", X stayed with Two, while Four was sent to Elsewhere on Earth along with the 14 contestants who chose to stay in BFB. He was later taken back in "X Marks the Spot".



X Finds Out His Value

X's first appearance was in a 2008 animation X Finds Out His Value along with Four, nine years before first appearing in BFB, with Four possibly making up as a host and running gag because of the season they first come back in. This also shows that X doesn't refer to the English letter, but the algebraic variable or the mathematical symbol of multiplication.

Battle for BFDI

X played a major role in the challenge in "Getting Teardrop to Talk". The contestants had to return his baskets back to X, who was standing on a tall platform, to avoid elimination. At the end of the episode, X puts on 4 of his baskets on the night, causing him to spin fast eventually.

X and 4

X with a basket

In "Lick Your Way to Freedom", X collaborates in the Cake at Stake as the character who throws the cakes, with Four being the one who says who is safe and who goes home/gets eliminated. Later in the episode, he warns Beep that Four won't like the fact that Roboty was missing. Once Beep loses, X tells them that one of them will be eliminated.

In "Why Would You Do This on a Swingset", X reminds Four that it's called Cake at Stake, and not Brake at Flake, prompting Four to insult X. Four later causes X to cry when they say that nobody noticed he was gone (despite Cloudy noticing).

In "Today's Very Special Episode", Four once again causes X to cry during Cake at Stake when X got the number of votes wrong. X also translates Four's muffled speech. X assists Four in placing the team tags on the rating scale during the challenge and offers his opinion on iance's and Death P.A.C.T.'s make-overs. The Loser's make-over was a papier-mâché mold which was encasing X, which may have contributed to their low placing, at 7th.

In "Fortunate Ben", X insulted Larry as, after Four started screeching, he stated that he is a "disgrace to the entire art community." Four said that he was thrown in the limb reattachment center, but when Beep collided with the cliff in the challenge, he thanks the ground. In the stinger, he is "dancing" (on which is swinging its hands) with 2 singers, one distorted, and one low-pitched in the audio.

In "Four Goes Too Far", X first appeared at Cake at Stake. Four asked X who's also safe. X answered by mentioning all of the contestants from Beep except for Cloudy, David and Roboty. When A Better Name Than That was pushing davemadson to the sledding, they also have got X, then Four. X ran away and was hiding in one of his baskets off-screen. X was not seen in this episode and beyond this event until the beginning of the 8th episode.

In "The Liar Ball You Don't Want", X is hiding behind a fragment of a Jawbreaker (this, however, was not shown onscreen, instead shown in a flashback in the 9th episode).


Gelatin biting X

In "Questions Answered", the top of X is seen in Fries' box. Gelatin describes them as swollen fries.

X returns in "This Episode Is About Basketball", X is seen among Fries' fries again. Gelatin tries to take some of them but ends up biting X after he is exposed. X screams out of pain, causing him to be found. X, when questioned, revealed that he ran away after Four got multiplied and hid the whole time because he got scared. Donut, sick of hosting, puts X into his position. X accidentally reads the voting results backward, revealing the results from most voted to least (i.e. saying that Stapy got the most votes at the start while Foldy got the least at the end) rather than the opposite. Later X tries to think of a challenge, and after some time, decides on a basketball contest. At the end of the episode, Donut is walking past X, and tells him "Good job today." X simply smiles in response.

In "Enter The Exit", X approaches Cloudy. Cloudy tells him that he has missed Balloony, and asks if he can recover him. X interrupts him, and says that he cannot recover him, however, he does tell him that he is safe. Later, in Cake at Stake, X reads the voting results for Beep, until it went down to David being eliminated. Because of his elimination, David quickly runs away. X chases him down and managed to catch up to him, shoving him inside his head. Eventually, once that is cleared up, X returns, only to find the contestants arguing. X grabs their attention to tell them the 10th contest, however, he gets interrupted by Clock by telling them to "bring back Four". Once Four was extracted from Donut by Firey and shaped by Pin, X missed him and had hugged him.

In "Get to the Top in 500 Steps", X confirms to Four that he missed a lot and shows what to do in the challenge while Four describes the challenge.

In "What Do You Think of Roleplay?", X (disguised as Four) and Four (disguised as X) are discovered that they've switched minds because Four (disguised as X) can't bring back contestants and X can (Though it is implied, due to the change in personalities).

He is later heard disguised as Four when iance was declared safe, making a joke about Team Ice Cube! being up for elimination. Four (disguised as X) says that the joke was horrible, and X answers with the fact that, since they switched bodies again, Four technically told the joke. They start to argue, but eventually, Four gives up.

In "Return of the Rocket Ship", X asks Four if Ice Cube can stay to watch Team Ice Cube!'s elimination. Four reluctantly agrees.

Later, X is seen standing next to Four. They stand there motionless for a little while, then X busts a hole in the ground and goes hurdling towards the center of the earth at 2,763 miles per hour, to find his treasure. The challenge of the episode is to find X's treasure before he does.

As X is on his way to the treasure, he receives a thought from Tennis Ball that says "X is stupid". X's smile turns to a frown. At this time, X was thinking about his treasure, which is various emeralds underground, and the coordinates where some of them are located.

In "Don't Dig Straight Down", X isn't seen until the very end at the stinger. He is still in the lava and asks "Why AM I doing this?" and continues to swim through the lava for no particular reason.

In "The Four is Lava", X jumps out of the lava and flies into the sky, pointing down at Four to indicate his location for the contestants to go to for the challenge.

In "The Escape From Four", X comes in and offers Four an orange juice box to make him feel better, though Four does not respond due to the fire (made by Firey Jr.). Later, X offers him an apple juice box but Four interprets it as X wanting to leave to co-host Two's show. X tries to explain himself but Four tells him to go, not listening. For the rest of the episode, X just stands near Two with an expressionless gaze.

In "X Marks the Spot", X is seen playing patty cake with Two when Four Colored Team arrives to take him back. Teardrop tries to grab X, but Pin stops her and grabs X back. The TPOT contestants all agree that X is the best host since he is the nicest one out of Four or Two. X gets hesitant hearing that he’s gonna be glued to the ground, and is splashed with paint later. Four Colored Team then throws a lasso around X, but the rope breaks and X lands on Loser's saliva spot. In the stinger, X was indifferent about being back at first, but gets happy when Four says he's good at patty cake.

In "Take the Tower", X gets upset with Four for screeching Lollipop, when Four apparently promised not to screech anymore. X hosts the Cake at Stake and replaces Four as the one who disposes the eliminated contestants, who now get sent to BRB. After Four explains the challenge, X shows the contestants some rocks they can use to throw at each other's towers and starts the contest. X is later revealed to be standing at the bottom of a cliff, allowing all of the rocks the contestants throw to land on him. When the contest is over, X and Four determine which team won and is up for elimination, based on the status of the towers. Along with also giving the team's their names.

In "How Loe Can You Grow?", X and Four are angry at some of the contestants for running over his aloe vera garden 73 times. As a result, X gathers all of the contestants together to tell them to respect his garden. Before he can continue, Firey points out how it's time for Cake at Stake. As the safe contestants grab their salt lamps, X makes worrying noises, hoping that they don't step on his plants. X then snaps his fingers to send Spongy away. After Bubble tells X that aloe vera can't grow in the biome because of there being to little sun, Four makes the contest to improve the sun, to help the aloe vera grow. X later asks Bubble how she knows so much about aloe vera, and she answers saying that it helps her keep her skin moist so that she doesn't pop from dryness. Lollipop then demands an answer from X since he got one from Bubble. Specifically as to why he is growing aloe vera. X whispers his answer to Lollipop and she is shocked at what he says. Lollipop then tells X that she will avenge him. The Have Nots eventually fire a laser at the sun, which makes the sun hotter, and makes the aloe vera grow faster. Though it also causes X be set ablaze by sunburn. Four supplies the contestants with ice to put the fire out, but they instead fly into space to dump it on the sun. During the stinger, X is still on fire, so Four decides to make X's problem the next episode's challenge.

In "A Taste of Space", X is still burning from the last episode, so the contest is to cool X down. The Have Nots and Have Cots spend the entire episode trying to find ways to cool X, while simultaneously making it warm for his garden without burning him. X at first is mostly generous with how he distributes the points to the teams, but progressively acts more irrationally, along with Four. Despite harming X being the only thing that could make the team's lose points, X begins subtracting points for completely unrelated reasons, like being mean. Eventually getting to the point where X and Four stop adding points all together, and just subtract them over minor things. The contest later ends when times up, but X is still on fire. Leafy decides to pour ice on X and that keeps X cooled down for good, so the Have Cots win. In the stinger ending, because X's garden was burnt, he has Flower act as the entire garden.

In "Let's Raid The Warehouse", Four reminds X to snap his fingers to eliminate Loser. For the contest, X tells the contestants to decide who will shop for gifts and who will receive them. X later uses Flower to test if his satisfaction detector works, it scans that Flower rates being in a pot as 2/10. When the shoppers return, X uses the satisfaction detector on each receiver.

In "Who Stole Donut's Diary?", Four says that he needs to help X untwist his nubs. When the contestants are lifted up to the BRB, Blocky compliments X's garden, causing X to randomly appear to thank Blocky, and accidentally fly off into the clouds. He's seen again in the courtroom, thinking he would be the judge for the contest until Four says that's what he's doing. X ends up not being interested in anything going on in the courtroom and uses Firey and Leafy as an excuse to leave. X catches Firey returning the diary and teleports back to Four to tell him. Four scans X's brain to find out who stole the diary, which X seems thrilled about, along with hoping that Four will keep his secrets. X later rushes back to grab the diary and brings it to Four.

In "Fashion For Your Face!", X hosts the Cake at Stake alone due to Four being jailed. Before he starts, he asks why the Have Cots are wearing ugly sweaters. The Have Cots all inch closer towards X to warn him about Flower, but agree there’s no point since she’s on her way. After snapping Bubble to the BRB, Flower arrives and kicks X in the sky. X doesn’t appear again until the ending when he announces that the Have Cots are safe and the Have Nots are up for elimination.

X hardly appears in "The Game Has Changed". Only being present to announce the new stage in the game with the final 7 and telling Gelatin that he likes baskets.


Main article: X/Relationships


Non-canon deaths:

  1. "BFDI's Road to Half a Billion Views": Killed by Tennis Ball by squaring X to -1, making him imaginary.


Total kills: 1

Character Number of times killed Episodes
Bubble 1 "Enter The Exit"


  • X's true value as a math variable is 7, as seen in "X Finds Out His Value", though in BFB, Four says he doesn't know his value.
    • The equation to figure out X's value was 2x+4+x = 8+2(3+x)-3.
  • X appears in the game Tidepool as a level 24 creature.
  • According to Four, X has a collection of baskets.
    • X has around 40 baskets.
  • In "Getting Teardrop to Talk", when X receives a basket from The Losers!, he says, "Yay! So much value!", which may be a reference to "X Finds Out His Value".
  • He has a somewhat sandy or stress ball-like texture, shown by Liy squishing him.
  • X's voice in "X Finds Out His Value" sounds very similar to Ice Cube's original voice.
  • In "Today's Very Special Episode", he said he does not like roleplaying.
  • X made an appearance in The JingJing Squisher, along with Ruby and Tennis Ball.
    • However, The JingJing Squisher is non-canon.
  • According to Cary in his reaction to "Getting Teardrop to Talk", X is 20 times larger than a contestant, due to the size of his baskets, though this was facetious.
  • He is of the first characters (not counting the limbless characters) to not have stick-figure arms or legs in the series, the other being Four.
  • X has no gender, along with Four, because in his world they don't "have that".
  • X has never been proven to be a multiplication symbol as well as a math variable because he ran away when Golf Ball tried to multiply him, Donut (who functioned as a Zero), and Four in "Four Goes Too Far".
  • X sometimes forms himself in the shape of an arrow (🡩), as seen in "Lick Your Way to Freedom" and "The Four is Lava".
  • X has the shortest name out of everyone on BFB, at 1 character.
  • X is also the Roman numeral for the number ten (10).
  • For whatever reason, X feels pain from being on fire but not when moving through molten magma.
  • "How Loe Can You Grow?" shows that X, while still put in a lot of pain, is far more resistant to fire than Four, as he doesn't become disoriented and dizzy from just the smallest touch.
  • In "The Game Has Changed", it is revealed that his favorite thing is baskets.


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AnnouncerFlower Speaker BoxFirey Speaker BoxPuffball Speaker BoxTVFourXTwoDonutHelloKevin

Math symbols
Numbers: ZeroOneTwoThreeFourFiveSixSevenEightNineFourteen


Other symbols: DonutPiAsteriskPlusInfinityFour and X put togetherNintySixVariations of Four

Interactions with Everyone, Four, Donut
Other content X's Alarm Clock, Baskets, X Finds Out His Value
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