Alter Ego is an artificial doppelganger of LarryBoy. He appears as the tertiary antagonist of LarryBoy: The Cartoon Adventures: Leggo My Ego. After the Alchemist sprayed LarryBoy with his new Ego Spray, Mother Pearl tricked him into insulting the citizens of Bumblyburg, which resulted in the entire town shrinking. The Alchemist then rounded up the citizens and trapped them in his lair, where LarryBoy eventually tracked them. However, Pearl prepared the Altered Ego Machine as a contingency plan, which turned the Ego Cloud residue into a "supercharged" version of LarryBoy.
Alter Ego is identical in appearance to LarryBoy, but with a different color scheme, yellow eyes and an inflated head, which is symbolic of and proportional to LarryBoy's ego. Anytime LarryBoy tries to insult someone, including Alter Ego himself, his head grows larger and he becomes stronger. Larryboy is eventually able to defeat him by complementing all those he had put down, causing Alter Ego to shrink into nonexistence and the citizens of Bumblyburg to return to normal size.