The Greatest American Hero. Soon to be a major motion picture, probably starring Will Ferrell or Jack Black. This TV show features probably the most archetypal semi-competent hero, complete with out-of-control flying and crashing into things. Ralph Hinkley loses the instruction manual for his super-suit and is stuck trying to figure out how to control its awesome powers by himself.
Green Hornet. No, not the original radio or TV versions of the Batman-esque crime-fighter — stop writing those angry comments! — but we're getting the distinct impression the upcoming Seth Rogen movie will feature a sloppy hero whose sidekick, Kato, is the famous and can-do member of the duo.
Ambush Bug. Actually, is Ambush Bug even a hero? In his first appearance (which I have somewhere, and which is probably worth a whole dollar now) the teleporting insect guy tries to assassinate the mayor of Metropolis. But he quickly becomes a kinda-sorta superhero, who mostly mocks the conventions and tropes of comics and gets killed over and over again. He also fails to save his doll sidekick, Cheeks The Toy Wonder, from being dismembered. Poor Cheeks.
Most of The Tick's supporting cast. At least in the animated TV show (It's been forever since I read the comics), the Tick is a semi-competent hero who often misses what's right in front of him. But at least he manages to defeat his enemies most of the time, with the help of his sidekick Arthur. Most of the other heroes i the Tick's world, like Die Fledermaus, American Maid and Sewer Urchin, are too self-absorbed or silly to be much use most of the time.
Most of the cast of Jim Valentino's normalman. Normalman crashes on a planet where he's the only non-superhero, but most of the superheroes he meets are worse than useless. Sure, Captain Everything has every super power ever, but he's so dim-witted he usually just makes matters worse. And Levram's main superhero team is too busy taking attendance to do anything else.
The Legion Of Substitute Heroes. They're the superheroes whose powers aren't cool or useful enough to join the future Legion of Super Heroes, but they keep trying anyway, and finally do save the world from an alien plant invasion. Antenna Lad can tune into radio broadcasts from any era, but only at random. Chlorophyll Kid can make plants grow fast. Color Kid can change the color of any object. Infectious Lass can inflict disease, but has a hard time aiming this ability properly. Etc. etc.
Rod Rescueman is a bumbling superhero in the animated movie Twice Upon A Time. He's got his superhero learner's permit, which is just a blank piece of paper (but it's notarized!). Attempting a practice run at rescuing a "damsel in distress," he inhales all the flames around her — then breathes fire at her, singeing her to a crisp.
The Inferior Five. Another parody superhero team, they have the requisite lame or out-of-control powers. "He can fly — if the wind's with him!" "She's stronger than an Ox — and almost as smart!" Ha ha, aaaaah yeah. Anyway, weirdly enough they had their own title that lasted 12 issues.
Irving Forbush. Marvel Comics' semi-mascot and hero of its Not Brand Echh comic, Forbush Man wears a crockpot on his head and stumbles through a series of wacky adventures.
Major Bummer. Soon to be a major motion picture (well, according to IMDB anyway), this short-lived 1990s comic was about a slacker who accidentally gets superpowers from aliens. But he just wants to sit around on his couch and watch TV. Unfortunately, the aliens also cause him to attract supervillains, including a Nazi dinosaur called Tyrannosaurus Reich.
Mystery Men. Already a major motion picture! William H. Macy, Ben Stiller and Hank Azaria are loser superheroes: Macy's The Shoveler, who can handle a shovel, Stiller's Mr. Furious, who has rage powers, and Azaria's "effete British superhero" The Blue Raja. Loosely based on the awesome Flaming Carrot comic by Bob Burden, this movie shows second-rate superheroes who finally do triumph over the A-list supervillain Casanova Frankenstein.
Kinnukiman was one of the most influential characters in the Japanese Shonen Jump anthology comic back in the day — a weak superhero that you'd call on if all the other, better heroes weren't available. A muscle-bound idiot, he was always getting into wacky scrapes. Later, he turned out to be an alien prince, and he went off to fight in an intergalactic wrestling federation.
Nuklear Man: Like Hancock, the hero of Brian Clevinger's novel The Nuklear Age has amnesia, and can't remember anything before he appeared in the rubble of a nuclear attack on Metroville's power station. Also like Hancock, he has Superman-esque powers and is totally self-absorbed and obnoxious... plus, he's easily distracted by shiny objects.
Superflop was the alter ego of British comedian Les Dawson, the superhero who failed utterly to protect the town of Leeds from the Masked Fred. (Dawson's show Sez Les, regularly featured John Cleese and Olivia Newton John — a combination that' s hard to imagine.) Superflop also got to star in his own comic strip in British comics magazine Look-In.
The Roach is the all-purpose stand-in for every lame superhero, in Dave Sim's misanthropic comic Cerebus. The Roach's other guises include Wolveroach, MoonRoach (a take-off on obscure superhero Moon Knight) and Punisheroach.
Super Melvin is possibly the dumbest ventriloquist's dummy of all time, operated by ventriloquist Jeff Dunham. Here's a clip of his act, from Comedy Central.
Zeroman was an animated series a few years ago, starring Leslie Nielsen as the ne'erdowell protector of Fair City, the alter ego of mailman Les Mutton.
Webcomic VG Cats features Pantsman, the alter ego of the comic's author, who disguises his identity by wearing underpants on his head.
Demolition Man. Poor D-Man. He started out so promising, as a super-wrestler who refused to throw a fight with the Thing from the Fantastic Four. (How exactly do you throw a fight with the Thing anyway? Lose more?) Later, it turned out he was addicted to super-strength drugs and had to kick. Finally, in the pages of Daredevil, he went nuts and started stealing jewelry thinking he was collecting infinity gems for a "Cosmic Gamemaster." He was living in a pitiful sewer lair, until Ben Urich sent D-Man's idol Daredevil to get him out of there.
Red Tornado. The original Red Tornado was Abigail "Ma" Hunkel, who put a saucepan (yes, again) on her head and went out to fight crime. But she ripped her pants and had to go home again. Later, she was replaced by an android that used to be evil but isn't any more, who has the awesome power of making wind. Yeah.
Wonderella is sort of a ditzy female version of Superman, in the webcomic The Adventures Of Wonderella.
Commenters daviddonne and Johnny Zito point out that I somehow forgot the Great Lakes Avengers, the midwestern branch of Marvel Comics' flagship super-team. They're mostly pretty useless, like Mr. Immortal, who's like Torchwood's Captain Jack — kill him and he just bounces back. But the group has a ringer: Squirrel Girl, who can control squirrels and somehow manages to defeat Doctor Doom and a number of other A-list supervillains single-handed.
And then commenter Trystero pointed out I missed The Pro, a sex worker who gets superpowers from meddling aliens. She's actually quite an effective superhero, but she's also a bad role model, urinating on a vanquished foe and using her superspeed to give tons of blow jobs for a quick profit. You can read the whole thing here, for now at least, but be warned — it's pretty NSFW.