While not technically considered an "official" ego, Robbie the Zombie has become quite popular in the Jacksepticeye community, and has quickly become a favorite among much of the community.
Robbie has no set "canon" personality, but he's depicted to have a very mellow, docile, and mild-mannered personality by the fandom, despite how he's shown in the thumbnail of Jack's video where he made his first (and only) appearance: "ZOMBIE MODE | Player Unknown's Battlegrounds #10 w/ Mark, Bob & Wade".
He's shown to be very sweet despite his ghoulish appearance, and he's been described to have the mentality of a young child in terms of how he processes things that are going on around him. He has trouble speaking, and tends to speak in small words or chunks of sentences, but does his best with learning how to speak, even if it's very slowly. While he's depicted to have very slow cognitive skills, he's much smarter than people give him credit for, and he only wants to get along with everyone and do his best at being an ego.