Classics:

• Frankenstein (1931)
• Bride of Frankenstein
• Son of Frankenstein
• Metropolis
• The Cabinet of Dr. Caligari
• The Rocky Horror Picture

More recent:

• Young Frankenstein
• Weird Science (1985)
• The Brain That Wouldn't Die
• Re-animator
• Bride of Re-animator
• The City of Lost Children
• Island of lost souls
• Horrors of Malformed Men
• Dr. Otto and the Riddle of the Gloom Beam
• The Fly
• Frankenweenie
• The Man With Two Brains
• Human centipede movies

Movies with some mad scientist parts:

• MAD GOD
• Batman & Robin
• TMNT mutant mayhem
• Body Melt
• Megamind
• Shock treatment