D.C. Simpson (originally David Craig Simpson, and then Dana Claire Simpson after her sex change) is the creator of Ozy and Millie. Beyond that comic, people haven't taken much notice of her work. Ozy and Millie was the most noteworthy of her creations, having been given semi-mainstream attention in its early days. Since then, things got a little shaky.
Aside from Ozy and Millie, she was dabbling in political comics with I Drew This!, which expoused her, at the time, liberal political views. She's since shifted farther to the left, now identifying as a socialist, and she got even more political in 2009 with Raine Dog, a comic that's attracted a lot of negative attention, including backlash from her fanbase, due to the Unfortunate Implications of the comic's allegory.
The comic originally started off as a deconstruction of the relationship between cartoon animals and cartoon humans in contrast to real-life relationships between humans and animals. Then Simpson started using the comic as a soapbox for her political views, publishing a comic that had nothing to do with the main story where Raine, Breaking the Fourth Wall, slammed the Republicans using a not so subtle Red State/Blue State commentary (seemingly the specific reason Raine was drawn with blue fur).
Then...things got weirder when Simpson tried to force Author Tract relating to her sex change and transgender life in the United States, but the allegory brought up too many Unfortunate Implications since it involved Raine Dog making out with a young boy. When members of a fan message board said that Simpson was Jumping the Shark, she out and out disavowed that board.
Since then, not much has happened with her career. In 2009, she won Amazon.com's "Comic Strip Superstar" contest with Girl, a comic about a young girl. Fans were a little more favorable to this one than Raine Dog, but the comic was still poorly received due to the fact that many of the jokes were recycled from Ozy and Millie. This comic was supposed to be syndicated by Andrews McMeel Universal, but was basically Vaporware for a while. Simpson retooled the comic into Heavenly Nostrils, the story of a human girl and her unicorn friend, which is currently running on Go Comics.
She also attempted to restart Raine Dog, but encountered negative fan response to the Unfortunate Implications of Raine standing in for Martin Luther King. It's basically an Orphaned Series at this point.