Who's This? Brainiac 5's biggest mistake.
How you could have heard of him: Fans of the LSH Animated Series might recognize the name Computo as the team's computer system, though he never got to become a villain.
Example story: Justice League Adventures #28 (April 2004) "Future Imperfect" by Jason Hall, Min S. Ku and Ty Templeton
Of course, it's a Justice League story, so it's going to take a while before Computer - sorry, C.O.M.P.U.T.O. - appears. Our story actually begins with the creation of Kilg%re, a Luddite turned into a tech-hating ghost in the machine, who will destroy Metropolis in a nuclear holocaust because people are so fixated on their (checks date) palm pilots. But as the reaction ticks down to zero, Kilg%re escapes to the future via a temporal portal, with Wonder Woman, Green Lantern, Flash and Hawkgirl just behind. That future? You guessed it, the Legion's (2980 to be exact). And it's a sort of remix of various iterations, with Andromeda in a relationship with Brainiac 5, a non-jerk Quantum Kid I, and Phantom Girl dressed as Apparition, working out of the original "Fortress Lad" HQ. Kent Shakespeare is a Clark-like reporter lurking outside. The other Legionnaires are off Earth because of a jail break on Takron-Galtos, but sh%t's about to hit the fan as Kilg%re starts infecting the future's computer network. Brainiac "don't call me Brainy" 5 already has a solution, and it makes use of C.O.M.P.U.T.O. (ah, there we go).
It's not THE Computo exactly, but it's a fun little tale that allows us to see him as both a help and threat, even if someone else is at the controls. And in a way, it gives DCAU Brainiac 5 the chance to redeem Brainiac 5 for the monster's invention, doesn't it?
Who's Next? A great white hunter/golden gorilla combo.