Vagary

Vagary is the first boss of Doom 3. She resembles a half spider woman with her lower body of that of a spider and her upper body is a woman's upper body. She is synonymous to the Spider Mastermind in Classic Doom. However, unlike the Spider Mastermind, the Vagary is weak compared to the other bosses in Doom 3. Her attacks are simple melee and telekinesis. Her abdomen contains a malformed human fetus. Later on in the game, two more Vagaris are fought, but these are red colored.

Trivia
In the Making of Doom 3 book, the equation "Sexy + Gross = Creepy." was used to describe the Vagary.