Starla

 Starla Gutsmandottir, also known as Muscle Woman, is an obese, green woman. She is in like appearance as Muscle Man. She works at Icy & Hot Jewelry & Apparel. She developed a crush on Mordecai and was the girlfriend of two other boys as it indicated with her lower back tattoo (she first dated Muscle Man, then Steve, then Muscle Man again, and then Mordecai, before dating Muscle Man again). When Mordecai broke up with her, she became extremely angry, destroying everything in her path, a helicopter. A news reporter in that helicopter even reported her as a "crazed woman on a rampage" before the deadly explosion, killing him. She is back together with Muscle Man after he expressed his feelings towards her at the end of the episode.

Major Appearances

 * "Muscle Woman"
 * "Fancy Restaurant"
 * "Pie Contest"
 * "Bald Spot"
 * "The Longest Weekend"
 * "Do or Diaper"

Minor (or Mentioned) Appearances
Overall: 8 Appearances
 * "Trucker Hall of Fame" (Flashback)
 * "The Christmas Special" (Non-speaking cameo)

Relationships
Starla has had a number of relationships with different men, including Muscle Man.

Muscle Man
Starla and Muscle Man's first relationship went on for awhile, then they broke up for a while. They began dating again for the second time, but then, Starla broke up with him because she didn't like that Muscle Man wasn't showing his feelings. They then got back together. They are still in a relationship.

Steve
Starla's unseen second boyfriend. They broke up for unknown reasons.

Mordecai
Starla's third boyfriend. However, Mordecai did not want to be in a relationship with her. They broke up because Mordecai told her they're not in a relationship, as a big plan to just get Starla and Muscle Man together because Mordecai already has a crush on Margaret. After this they are shown as friends as he helps Muscle Man maintain the relationship.

Margaret and Eileen
Starla seems to be close friends with them both as shown in The Longest Weekend.

Trivia

 * Starla is the second female antagonist on Regular Show. The first one is Susan. However she is given more pro-tagonistic appearances.
 * She looks exactly like Muscle Man, but in female form. In an example of contrast, her hair is fixed into two ponytails at the sides of her head, but some of hair drops around her ears like Muscle Man.
 * As seen on her lower back tattoo, she has dated and broken up with Muscle Man twice.
 * She is mentioned in "Weekend at Benson's" as she and Muscle Man are still dating, she seems to like jazz music.
 * It appears that she has dated Muscle Man since high school. This was depicted in "Trucker Hall of Fame" when Muscle Man said that they were going to prom.
 * Starla returns in "Fancy Restaurant", where she takes Muscle Man to a fancy restaurant with her parents which Muscle Man gets nervous since he's not fancy.
 * She once dated a guy named Steve. It's proven on her back tattoo.
 * She is shown to appear frequently during season 3 and 4.
 * She dated Muscle Man, then Steve, then Muscle Man again, then Mordecai and she currently dated Muscle Man for the third time.
 * Part of Starla's last name makes a reference to the name Guts Man, one of Dr. Light's robots from the Mega Man series.