Viper (Keroro)

Viper is a villain in Sgt. Frog (also known as Keroro Gunso in Japan).

Original Viper
The first Viper who fights the Keroro Platoon because of a war between the Keronians and the Vipers, and was defeated by a technique used by Dororo. He reappears in Episode 121, where he appears as a cyborg who takes revenge on Dororo, but ends up capturing Chiroro and hides in Alien Street from the Space Police and the Keroro Plantoon. To keep himself from being spotted, he disguises himself as a chef in a ramen stand. When Keroro disguises himself as Viper and captures Karara in an effort to earn money, Viper takes off his disguise and attempts to defeat the fake Viper, proving that he does have some good in him. Viper's cyborg appearance is very reminiscent of Freiza, of Dragon Ball Z fame, when he became Mecha Freeza. His left half has been completely demolished and replaced with mechanical parts, his left eye is green and has a yellow scope as its pupil, a black tube appears on his head and leads to the back of his head, and the buster arm he had before has now been replaced with a mechanical claw. He has a son that was taken away by his ex-wife who he taught a technique on how to make the Tokyo Tower out of cherry stems.

Other Vipers
Viper is the name claimed by all members of the immediate and extended Viper family and friends. Each Viper character, upon entering the scene, will explain his or her relationship to the previous Viper. The first Viper fought the Keroro Platoon per the age old "snake versus frog" battle and thought it was his right to abuse the weaker Keronian. After all, snakes often ate frogs as part of their diet. However, with his defeat, each subsequent Viper has been on a vendetta against the Keroro Platoon. The exception is Viper Mother, who on Mother's Day, was only traveling to earth to visit her son, Viper.

Each member of the Viper Family is outfitted with a red jumpsuit, black belt, and right hand blaster. Variations of Viper and the Viper family can be seen in the Viper Wedding, Episode 74 "Surprising - Keroro Special Version, gero gero 30 minutes, 15 stories".