Alice Cooper's "No More Mr. Nice Guy" is about Cooper throwing down the gauntlet after his mother's church group reacted with disgust to his onstage antics. He contends he was actually a Nice Guy...but not anymore.
Subverted in Kid Cudi's "Man on the Moon (The Anthem)":
Kid Cudi: Maybe if I was a jerk to girls,
Instead of being nice and speaking kind words,
Then maybe it would be okay to say then,
I wasn't a good guy to begin with."
Many of Dino Attack RPG's main characters can be considered Nice Guys. This is especially true of primary characters, Ideal Heros, and medics. Some notable examples include Andrew, Hertz, Zenna, David, Pierce, Frozeen, and Montoya.
Bob McKellaway in Mary, Mary. Subverted in the end, when he prevents Mary from going away with Dirk by seizing her and shutting her in his closet.
Paris from Romeo and Juliet. The poor guy legitimately has no idea that his betrothed, Juliet, is in love with another man, and when she fakes her death, he visits her grave, intending to return every night. Even Romeo feels sorry for him after he kills him in desperate self-defense.