Doomsayer may refer to:

• A doomer or peaknik (believer in drastic consequences from the peak oil theory)
• A character class in Hell on Earth
• A person or doomsday cult claiming a doomsday prediction

• Polyptychus bernardii
• Polyptychus boisduvali
• Polyptychus brevis
• Polyptychus burorum
• Polyptychus calcareus
• Polyptychus chinensis
• Polyptychus claudiae
• Polyptychus compar
• Polyptychus consanguineus
• Polyptychus consimilis
• Polyptychus contraria
• Polyptychus coryndoni
• Polyptychus delicatus
• Polyptychus dentatus
• Polyptychus digitatus
• Polyptychus distensus
• Polyptychus draconis
• Polyptychus enodia
• Polyptychus enodius
• Polyptychus erlangeri
• Polyptychus erosus
• Polyptychus falcatus
• Polyptychus ferroseus
• Polyptychus foliaceus
• Polyptychus fulgurans