Penny is the love interest of both Dr. Horrible (a supervillain) and Captain Hammer (his superhero archenemy who nevertheless is even worse) in the tragicomedy internet miniseries Dr. Horrible's Sing-Along Blog. She is the only genuinely good character, as she is generous, idealistic, and volunteers at a homeless shelter. She falls in love with the adversary, Captain Hammer, as he is a superhero (though she is unaware that he is ironically more villainous than Dr. Horrible, but later, during the "Everyone's a Hero" number, she finds out that he is a jerk). Eventually, at the end, Dr. Horrible inadvertently kills her (because Captain Hammer had refused to listen to his warnings about using the death ray, causing it to give him his first taste of pain) and her last words are that Captain Hammer will save her and Billy (unaware that he is Dr. Horrible) (due to having faith in heroes and presumably forgetting he was such a jerk). She then dies, much to his remorse, causing him to declare Pyrric victory, and to enter the Evil League of Evil. That gives him everything he ever wanted except what he wanted the most. She was played by Felicia Day.

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