Nightmare is a bio-weapon that serves its creator, Mundus. It is the boss of Mission 16: Nightmare of Darkness, Mission 18: Spirit Stone, "Elixir" and Mission 20: Showdown with Nightmare in Devil May Cry. There are two weapons fashioned after it: Nightmare-β, which appears in Devil May Cry; and Nightmare-γ in Devil May Cry 2.
Nightmare (Devil May Cry) has been suggested to play 13 roles. Click below to see other actors suggested for each role, and vote for who you think would play the role best.