I was going to say that but I thought it had to be another actor from Star Trek. Perhaps Q's crazy cousin is named Mork?
Robbert Knepper who was T-Bag from prison break. T-Bag was like a more mischievous Q but without the powers.
^ And doesn't Lady Q give off a huge Morticia vibe? "Don't torture yourself, Q. That's my job." Speaking of Addamses: How about Christopher Lloyd as a Q? I can totally see that.
You know Christopher Lloyd would pull that off quite well I think. Certainly he's versatile enough to cover Q's mood swings.