Here’s some concepts of villainy for Randy Cunningham - McFist and his henchman the Viceroy.
I don’t remember the exact description I had for McFist but I knew he was supposed to be some kind of corporate jerk, probably former military, with his defining feature being a robotic arm controlled by a fish brain. Pretty sure it was a fish brain. McFist I think saw the biggest changes from sketches to how he appears in the show, with concept stage McFist being a stocky block of a man. Looks like he slimmed down in the end, but here he’s a bit more of a cybernetic monster jerk. I can’t recall if the fish brain’s old-school arcade joystick made it into final animation, but I thought it was funny that that arm would be controlled with as simple an interface as a joystick.
Viceroy was actually one of my favorite dudes to figure out and I think he remains relatively unaltered from concept to final animated form. Described as kind of a super-genious henchman dandy, I ended up going with something inspired by Richard Ayoade’s Moss from the IT Crowd, and Sam Jackson’s Mr. Glass from unbreakable.