Terra the earthworm is introduced in 1/0 after the Interactive Author initially didn't want any female characters. He wanted his three male characters to remain romantically frustrated, but when it became clear Ho Yay would be the inevitable result, he relented and added her. To spite his characters, he made her a lesbian, so the guys would still be frustrated. The cast grows somewhat over time (six characters at the end), but Terra remains the only female in the whole strip.
The primary protagonist group of 8-Bit Theater would be Fighter, Thief, Red Mage, and Black Mage, plus White Mage. Of the five, only White Mage is female, and she only shows up occasionally.
In Charby the Vampirate LaBelle is the only female in her pack, and when she leaves it she joins up with another group that consists of all males outside of herself. Han is the only woman employed as one of King Samrick's Royal Justiciars.
Hanna Is Not a Boy's Name has an almost all-male cast. Out of half-a-dozen protagonists, only one is a girl. The only other recurring woman is a villain.
In the Insecticomics, Kickback claimsnote He's lying that viewers had complained that the comic didn't have enough female characters (there's half a dozen male robots introduced in the first dozen or so strips) and uses this as a justification to start a vote over changing Laserbeak's gender to female. This makes her the only robot-female for the next fifty strips (and only the second female in the work). While the cast isn't a Gender-Equal Ensemble, several more females are added.
The Order of the Stick's eponymous group consists of four males, one female, and an elf (although elves tend to have genders in this series, the androgyny of Vaarsuvius is a Running Gag). While other female characters have become prominent, notably Celia, the six-character band has, at most, Two Girls to a Team.
Six Pack Of Otters: We have not yet been introduced to all six of the Otters that the title implies...but of the five that we have met, four are male. And the fifth, female Otter's presence is felt mostly by the other four (male) cast-member's reaction to her: she's not unseen, but she hasn't had a whole ton of screen-time either.
Linda Concarne is the only female regular in Triangle and Robert, a webcomic of shapes and... things. There's dozens of different characters, but only the one rectangle.