10. Darcy Lewis (Marvel Cinematic Universe)
I hesitated to include Darcy Lewis on this list because, at times, I actually had a soft spot for her (and Marvel obviously saw fit to bring her back for Thor: The Dark World), but even I can't deny that she was very irritating at times. Darcy is played by the genuinely funny Kat Dennings and is Jane Foster's (Natalie Portman's) research partner in the Marvel Cinematic Universe. Though not a scientist herself, she's pretty observant in comparison to those who are and, as a result, if she notices something first that no one else has noticed, she's pretty damn sarcastic about it, which is very irritating. She's also one of those annoying comic relief characters that superhero movies don't necessarily need, coming out with quirky and supposedly witty one-liners in otherwise serious situations - another highly annoying trait. All in all, Darcy isn't hideously annoying at all times, but she certainly can be sometimes.