When The Avengers started in 1963, The Wasp was the only female member, and the weakest. Then all the original members left in 1965, but there was still only one female, the Scarlet Witch, who was the weakest...at the time.
The Wasp herself eventually became a badass hero in her own right and she even led the Avengers.
Bloom County's cast had a series of strips dealing with the necessity of introducing a female character after the Supreme Court declared male-only clubs unconstitutional. ("Nothing's more 'male-only' than Bloom County! We've GOT to introduce a WOMAN!") Before, the comic strip had several notable reoccurring female characters including the feminist schoolteacher Ms. Harlow, who actually didlike men. Eventually, Ronald-Ann was created as a regular, who subverted the trope by not being The Chick. Rosebud the Basselope was also revealed to be female, much to the surprise of the cast. Unfortunately, it looks like this was retconned to oblivion.
Even more directly addressed in the not-a-sequel-series-I-swear, Outland. In the strip, a woman asked why all the well-known animal characters in comics and animation are all male; any female animal characters were just The Girlfriend. Opus announced that the strip was just about to hire the first major female animal character star to join the main cast, Hazel the Hedgehog. In a brilliant sequence that ran for weeks, she lampshaded why most animal characters are male. (Are we asking girls to identify with a "little pig-rodent"? Can she participate in a slapstick pie fight if depicting violence against females is taboo? Is she still her own distinct character if we have to put a bow on her head?)
According to Norwegian Scholar Jon Gisle, the population of Duckburg is about 80% male.
In The Doom Patrol Elasti-Girl was the only woman in the original team.
Alison Bechdel's Dykes To Watch Out For initially inverted this, with scarcely any male characters, partly as a response to the Smurfette principle (as discussed in The Indelible Alison Bechdel) and partly to force male readers to identify with the female characters, as women often have to identify with male characters. Over the last several years, more male characters have appeared; one of the main characters, Sparrow, had a long-term relationship and a child with a man named Stuart. This may have also been her accommodating what has become to be known as The Bechdel Test in her own work.
When the Fantastic Four started in 1961, the Invisible Girl was the only female member, and she was the weakest of the four (her force fields weren't invented till later).
When the Justice League of America started in 1960, Wonder Woman was the only female member, and though not necessarily the weakest, was certainly the most resembling. At least the early Gardner Fox stories treated her like the other members, and not like The Chick. Though she soon became the secretary at the JLA's meetings, taking minutes and so on. It took almost a decade before Black Canary became the second female member (and that was only after Wonder Woman had resigned; it would take several more years before there was more than one woman on the team).
In the original Justice Society of America comic (predating the Justice League by decades), Wonder Woman was the only female character, and had to be the secretary and never took part in storylines, so JLA Wonder Woman actually came out ahead. That was in the 1940s however, and the reason she didn't take part in storylines was because she had her own book. As a rule the JSA active members were limited to popular characters who didn't support their own title, and even Superman and Batman were limited by it. The JSA did, eventually, get a female character: Black Canary. Huh. Pattern?
To offset this, Earth 2, the 2012 modern reimagining of the JSA, has Hawkgirl as a founding member. Double points since she's not only a woman, but a Latina as well.
To add insult to injury, the JLA rejected a female member prior to letting Black Canary in: Hawkgirl was specifically disallowed, initially because the bylaws required they only let in one new member at a time, and they had just let in Hawkman. Later, she was kept out because her powers duplicated Hawkman's, so she brought nothing new to the table. Hawkman, of course, only has flight and scientific/detective skills (usually), thus is made completely redundant by Superman and Batman, but nobody moved to kick Hawkman out on these grounds. Hawkgirl was finally allowed in in the 70s, when the writers caught up with the sexual revolution.
Platinum was the only female member of the Metal Men. Tin later created Nameless, who didn't really do much other than act as his girlfriend. Right before the Cerebus SyndromeRetool, Doc Magnus created Distaff Counterparts of the team, but they were one-off characters. In recent years, the team finally gained a bona-fide second female member, Copper.
The Metal Men's schtick is that each has properties/abilities associated with their respective "metal". Nameless (who, like Tin, is made of ... well, tin) had exactly the same powers as Tin (who was himself probably the weakest of the metal men), but Tin had more experience, so there usually wasn't much for Nameless to do.
With the occasional exception of Xavin, Runaways inverts this by having, at most, 2 male characters in any team roster. Of those characters, only Victor has had superpowers constantly.
Rupert Bear had few female characters - Ottoline Otter (introduced about a couple of decades ago) and Tiger Lilly, not counting the mothers of the characters - and the main cast was mostly male. The CGI adaptation saw it fit to Gender Flip Ping Pong and Freida Fox.
In Scott Pilgrim, one of Ramona's evil ex-boyfriends is actually a girl. Justified by the fact Ramona is mostly heterosexual and only became bisexual during her "phase", so it's actually a surprise the group even includes a girl to begin with.
Named for Smurfette, the only female Smurf for years out of a population of 100.
Ironically, The Smurfscartoon actually toned this down, a little. While you could argue Smurfette is as much a stereotype as any other specific smurf, Peyo (their creator) caught some flak by admitting she was not intended to be a real heroic character at all, describing her in mostly childish ways. The Hanna-Barbera show only played this up in her origin, where she was created by Gargamel to disrupt the lives of the Smurfs. Otherwise, Smurfette is typically a strong-willed type who is often ready to take charge when necessary in Papa Smurf's absence. (In fact, in the conclusion of that origin story, she rescued the rest of them, single-handedly.)
Later, another female Smurf, the younger and more tomboyish Sassette, was created by similar means as Smurfette. The penultimate season added Nanny Smurf, who confusingly seems to have been a natural female Smurf.
The second movie expands the story, claiming that Smurfette was originally something called a "Naughty" before Papa Smurf's spell, created as a Distaff Counterpart of Smurfs (not truly evil, but incredibly mischievous). In the actual movie, Gargamel creates two more of these creatures named Vexy and Hackus - one male, one female - in order to discover how to use Papa Smurf's spell to turn them into true Smurfs. Gargamel's actual goal is to use a device to extract "smurf essence" from not only the real Smurfs, but from Vexy and Hackus as well once the spell is cast, considering them Unwitting Pawns. The two eventually turn against him and are taken in by the actual Smurfs.
Although, as noted in Donnie Darko, as a creation of Gargamel Smufette wasn't a true Smurf. Originally, the Smurfs were all male (or possibly asexual). One cartoon explained that smurfs did not reproduce the way most creatures did; a stork magically delivered them as infants on nights when there was a blue moon. Thus, gender was a moot point.
This was later spoofed in Fables. The founders of Smalltown were members of a Lilliput army (i.e. all men), until Thumbelina showed up. One member had to go find more of the magic barley seeds that she grew from because of mass riots and fighting over her.
In Hergé's The Adventures of Tintin comics, just about the only recurring female character is Bianca Castafiore, who's an impossible diva. Oh, and her maid.
Word of God says that Hergé had a lot of trouble drawing adult characters that weren't ugly or ridiculous (Tintin doesn't count, as the character design is almost childish and very simple anyway) - something that didn't bother Hergé when it came to men, but annoyed him greatly when drawing women. He actually started to get better at it in the latter albums, and a cute female character with a major role was introduced in "Tintin et l'Alph-Art", but this effort suffered Author Existence Failure.
The newspaper comic Tumbleweeds had two Smurfettes — Hildegarde Hamhocker among the townsfolk of Grimy Gulch, and Little Flower among the Poohawks. Aside from Hildegarde's little niece Echo, other female characters are extremely rare (if not non-existent) in the strip.
Silk Spectre II from Watchmen is the only female super-hero of the second generation. Furthermore, her central importance to the plot is that of her role as a woman, being a kept-girlfriend to Dr. Manhattan and then the love interest of Nite Owl II. However, this is a deconstruction, so it may be intentional to demonstrate the usual roles female characters played in the comic book genre ten to twenty years before "Watchmen".
The WWII era group originally had two females (Silk Spectre I and The Silhouette), but the latter was kicked out when it became known she was a lesbian. (As at least two males were known among the group to be closeted homosexuals, the commentary on sexism is definitely intentional.)
When the X-Men started in 1963, Jean Grey was the only female member, and the weakest (it was a decade before she got Phoenix powers).
Polaris, the second female to join the team, didn't join until 1969, although she has had a sporadic history with the team.
When the "New X-Men" started in 1975, Storm was the only female member. Though she certainly wasn't the weakest (and seeing as how Chris Claremont was writing, she wasn't alone for long, either).
Eventually, the X-Men became quite possibly the heaviest aversion of this trope in the entire genre. At some points in their history, female characters actually outnumbered the males.
As of 2013, one of the X-Men teams consists entirely of women.
The original incarnation of the Brotherhood of Evil Mutants had Scarlet Witch as its only female member, though also the weakest at the time (mostly due to her inexperience with her powers).
Averted during the "Sisterhood of Evil" era, when the three female members of the team carried on in the absence of the then incarcerated male members.
Lampshaded in Youngblood: Judgment Day, where Glory is keen to the idea of re-forming the Allies of Justice because she enjoys being the only woman in a team of men — it's implied that it makes her feel like she's the one in charge.
Inverted in Y: The Last Man where Yorick Brown spends most of the series as one of only two males (the other being his pet monkey) in a world full of women (most of whom try to kill him).