There are the obvious dream contestants that people bring up often (David Mitchel, Richard Ayoade, etc), but who would you love to see on the show that you rarely see people suggest?
Personally, I'd do ANYTHING to see Brennan Lee Mulligan on Taskmaster. He's creative enough to have some really clever solutions to tasks, but also competitive enough to spend half the episode arguing with Greg about why his loophole technically doesn't break the rules. He would be an absolute joy who'd steal any Season he's in.
Performing a task