I’d like to add Egg Fu to the gallery of lame supervillains. A giant egg with an oriental face painted on it and a very grabby moustache, woo-fucking-fu. One reasonably hard hit and he’s an omelet.
Of all the sorry freaks in Batman’s rogues gallery, the worst I’m aware of are Tweedle Dum and Tweedle Dee. Identical cousins (real names Deever and Dumfree Tweed) who actually looked like the egg-shaped monstrosities of the original illustration in Alice in Wonderland. They started out as henchmen for the Joker and then tried working on their own. The last I saw of them, they had been turned into idiots by botched brain-implant surgery at Arkham- a rather fitting conclusion to a pathetic career.
X, The Eliminator from Harvey Birdman: Attorney At Law is pretty lame, but that’s part of the humour- he’s actually a lot closer to a Harvey Birdman fanboy than an actual villain, and his Silver Death Console uses Vacuum Tubes instead of transistors. 
As written in the books he’s pretty scary, but I was seriously disappointed at how Voldemort turned out in the Harry Potter movies. It’s as though he thinks he can defeat Harry by flouncing him to death.
To quote myself in an earlier thread on the subject, my vote is for Turner D. Century. Seanbaby summed him up nicely.
I’d have to disagree with that. He’s a total wuss in and out of the books. His plots rely on the fact that every adult wizard in England is an idiot.
Xemnu, from the John Byrne second run She-Hulk. How are ya supposed to take a bad guy seriously when his tagline is “I have no mouth and I am mean!”
The Angry Red Herring or The Ottoan Empress.
But then again, in the TickVerse just about everyone has some lame in them.
I nominate the Demonwolf, aka the “Fusion-Phallused Violator of Worlds” from “Empowered.” He’s actually quite powerful when free, but he’s confined to an alien bondage device that saps his super powers, and now all he can do is watch TV and listen to talk radio and snark, and beg his captors to let him watch their 'filthy animal coupling." He also does a hilarious takeoff on Jack Kirby style villainous ranting, saying things like, “Your accursed tuck rule will avail you naught, Tom Brady!” as he watches TV.
He’s intended to be funny, but the important thing is, he is actually funny.
Nooooo!!! Not Ambush Bug.
His arch-nemesis: Argyle (or however it’s spelled)
That’s right, the super-hero is so lame he’s constantly worried about the evil machinations of an escaped sock.