|First Appearance:||"The wrath of Dark Kat"|
|Affiliations:||Independent, Katastrophe team (with Dark Kat and The Metallikats)|
|Vehicle:||Via his own plant manipulation|
|Voice Actor:||Frank Welker|
Dr. Elrod Purvis once worked at Megakat Biochemical Labs. He tried to steal an experimental regenerative formula he and Dr. N. Zyme were developing. He became covered in the formula when he fell down the stairs and the shock ultimately killed him. The chemicals revived him from death, mutating Purvis into a half-kat, half-snake, half-iguana creature. With expertise in the fields of biology, genetics and robotics, he sought to turn Megakat City into Mutation City and transform the residents into mutants like himself. He was able to turn people like Morbulus into monsters. Dr. Viper is by far the deadliest enemy of the SWAT Kats, and he and his creatures murdered a number of innocent people (including his former colleague Dr. N. Zyme) in the series. He was similar to the Spider-Man villain The Lizard, though by comparison, he is much more evil. He first appeared in "The Giant Bacteria." He last appeared in Mutation City. It's possible he returned back to normal since he was at the center of the anti-mutagen blast over the city in his last appearance, or he could have been killed. Voiced by Frank Welker in the original English version.
His reptilian mutation grants him the following:
- Durable Hide - his reptilian hide has allowed him to survive hits that would kill most kats
- Enhanced Strength - usually with his tail, he is capable of lifing full grown kats off the ground with it.
- Blood - his blood is a mutagenic chemical itself, as he fed mosquitos off of his hand, which then mutated in monstrous forms
Note: he may also have the ability to regenerate, as the formula that mutated him was designed for specifically that purpose.