Black Viper

Black Viper is a giant alien monster in the Contra video games, who officially appears as the final boss in Operation C and Contra 4. According to the manual for Contra 4, "she" is the "sister" of Red Falcon. In Operation C, it first appears as a robot and is then killed as a defenseless cell creature in a tube. In Contra 4, Black Viper is initially an insect-like monster, but then returns as a gigantic alien beast whose butt has to be destroyed and then entered, climbing through its insides to reach the brain setup inside the head, which is similar to the final boss of Contra 3, which also appeared in Contra 2. Because of this, it is difficult to determine whether those also count as appearances of Black Viper.