Yeah, Yunalesca is a whore.

IMO, it was Sephiroth in Kingdom Hearts. He'd always slash you right as you were trying to heal or pull off some big move, and he'd always do his gay Sin Harvest thing when you were too far away to stop him. It pissed me off so bad.

Another one is Dos Gigantes from Resident Evil 4. I'd always get double teamed trying to do the lava-pit-in-the-floor trick, and when I'd pull it off, the guy flailing in the lava would always somehow manage to grab me because of a weird glitch.