Dr. Sinister is a mad scientist, a one-time character, the titular villain and the main antagonist of the episode of the same name, featured in the fifth season of the original series, The Flintstones.
Dr. Sinister is a cruel, dangerous, ruthless, power-hungry, evil, and villainous mad scientist who wants to destroy the world with his World Destruction Machine, the most powerful and deadly invention ever.
Dr. Sinister is a tall and slender green-skinned man with a pointy head, a long nose and elf-like ears with thick black half moon-shaped eyebrows, a little tuft of red hair and red claw-like fingernails on his hands. Also, he wears a black circular glasses on his head and a black cloak.
- The Flintstones - "Dr. Sinister" (first and only animated appearance)
- The Flintstones: Big Trouble in Bedrock (last and only video game appearance)