| X | |
|---|---|
| Battle for Dream Island character | |
 X as he appears in Battle for Dream Island: The Power of Two | |
| First Episode Appearance |
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| Final Episode Appearance |
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| Created by | Cary and Micheal Huang |
| Character played by | Cary Huang (since X Finds Out His Value) YellowAngiru (The Official Four and X Plush only) |
| In-universe information | |
| Species | Algebralien |
| Gender | Male |
| Significant other | Co-host of the fourth season, Battle for BFDI/BFB Temporary co-host of the fifth season, Battle for Dream Island: The Power of Two |
| Home | Equation Playground |
X is a variable and the co-host of the fourth season of the Battle for Dream Island series, Battle for BFDI/BFB, created by Cary and Micheal Huang. While they are first officially introduced (within the Battle for Dream Island series) as the co-host of the season (Four being the main host), never making an appearance in any BFDI season prior to this, they do make their first appearance, alongside Four, in the 2008 educational video "X Finds Out His Value".
X's first appearance in BFB was in "Getting Teardrop to Talk" where they and Four started a competition to win "a BFDI" (a compilation of all episodes of BFDI and classic BFDIA) until "The Escape From Four", where Four's show split into two. X was intended to be the co host for TPOT until he was taken back to BFB in "X Marks the Spot".
For a short time, X became the main host of BFB from "This Episode Is About Basketball" (due to Donut resigning from hosting, and Four's absense) up until "Enter the Exit" (where Four returned, and ultimately resumed hosting).
X also appears in TPOT with Four as the chefs for the Hotel, with Clock helping them from "The Seven Wonders of Goiky" up until "Oneirophobe's Nightmare".
X temporarily co-hosts Battle for Dream Island: The Power of Two in the episode "The Power of Four" as a result of Two's depression due to Gaty going missing.
In 2018, X along with a best friend Four became the Official English language Jacknjellify YouTube channel mascots after a request by some fans.
Appearances[]
X Finds Out His Value and The Number Playground Chronicle![]
"X Finds Out His Value" (abbreviated XFOHV) is an animation made by jacknjellify. The video marks the debut of Four and X, two Algebraliens who would later become hosts in BFB. It was released on December 31, 2008 at 3:15:10 PM PST, an entire year before BFDI. Cary Huang made this as his first "serious" animation, intended for his pre-algebra class.
It is an educational animation aimed at children, showing them how to do basic algebra (specifically Solve for X). As of September 25, 2025, the video has 13,125,720 (13 million) views.
X makes his first appearance with Four in the 2008 educational video, X Finds Out His Value. He also appears in The Number Playground Chronicle!
The Tidepool[]
In the 2013 now discontinued Flash game, The Tidepool, X along with Four makes his cameo appearance in one of the levels.
Battle for Dream Island[]
X in the twenty-first episode of Season 4, Let's Raid The Warehouse
In the first episode of the fourth season, Battle for BFDI/BFB, titled "Getting Teardrop to Talk," X made their first canon appearance. They agreed with Four that it's too bad if the contestants have to live with dying forever. X is squished by Liy, who comments that they have a different texture from Four. Four then begins to screech the contestants for no apparent reason. X tries to get him to stop but gets screeched himself. X later gets up claiming they love the BFDI, only to get screeched again. X played a major role in the challenge. The contestants had to return his baskets back to X, who was standing on a tall platform, to avoid elimination. In the stinger of the episode, X puts on 4 of his baskets on his nubs, causing him to spin fast.
In the subsquent episodes of Season 4 except for episodes 9 and 10 (where he is a host), X is a co-host with Four (the main host).
X makes the return with Four in Battle for Dream Island: The Power of Two just two years after the finale of Season 4. In "The Great Goikian Bake-Off," They appear again with Four after a while as chefs for the hotel guests. They both fight off the contestants trying to steal their food using the Zappies.
In "The Power of Four", Four and X agree to take over hosting TPOT while Two mourns Gaty's disappearance. All the contestants gather on the hotel roof, where Four hosts Cake at Stake for Death P.A.C.T. Yet Again. Afterward, X takes over to host Cake at Stake for Team 2. X notes that the vote counts between contestants were much closer than those of Death P.A.C.T. Yet Again before playfully calling Black Hole greedy for receiving the most votes. He first turns to Snowball, announcing that he's the first safe with 24,157 votes. Next, he addresses Price Tag, who remains safe for the sixth time in a row with 23,559 votes.
In the 21st episode of Season 5, X will be the temporary main host due to Four being trapped by One.
Reception[]
Four and X in the fourth season, Battle for BFDI/BFB
As of the completion of Season 4, X is the third fan favorite host of any BFDI season, placing him in third place position ahead of Four, who is in first place position. On December 11, 2021, X plush became available to the shopping selection for sale for the first time with Four. 4 years later, in 2025, X figurine with Four became available for sale at the shopping selection for the first time, on May 29.