G1 Starscream
Starscream used to be a scientist, but now he's just a Decepticon who tries to take over, and it always ends in disaster. He's smart, but he's also a total failure.
"Starscream tried to take over Cybertron again, and it ended with him getting buried under a pile of scrap metal."
"I swear, every time Starscream makes a plan, it ends with him getting laughed at."
"Starscream's last plan was so bad, even Megatron was embarrassed."