Zilla is a kaiju introduced in the 1998 American remake of Godzilla. Unlike Godzilla, Zilla is not a lost dinosaur mutated by nuclear radiation, but an iguana who mutated while still in an egg, mercifully surviving the atom bomb tests in French Polynesia. He is also lacking his namesake's atomic breath in his movie appearances. While named Godzilla in the movie and subsequent animated series, Godzilla fans took to calling him G.I.N.O. (Godzilla In Name Only), Deanzilla, Devzilla and Trizilla, until Toho acquired the rights to the creature for an appearance in Godzilla Final Wars and changed his name to Zilla, feeling that the 1998 version had taken the 'God' out of Godzilla. Despite this, he is gaining a fanbase thanks to his unique design.
The only survivor from a clutch of iguana eggs, Zilla mutated heavily, growing to an enormous height and later attacking a number of fishing trawlers at sea. One survivor of a Japanese ship mistook the creature for a legendary sea-monster, Gojira, and this creature's name was the only thing he said while hospitalised. Zilla found his way to New York where he began searching for food and a place to lay his eggs after reproducing asexually. Eventually after being pursued by the military, he dived into the Hudson, where he was bombarded with torpedos. This seemed to have beaten Zilla, leaving the issue of an army of baby Zillas, freshly hatched in Madison Square Gardens. The stadium was obliterated, only for an unharmed Zilla to rise out of the rubble, enraged at the loss of his children, and pursue the survivors. He soon found himself entangled in the cables of the Brooklyn Bridge, unable to advance any further, whereupon the army hit him with several volleys of missiles, finally finishing Zilla off. One egg remained intact in the ruins of Madison Square Gardens however....
Godzilla: The Series
Around a year later, a race of alien invaders began enslaving the planet's monsters, including the fully-grown Zilla Junior. One of the most formidable monsters in their control however, was the first Zilla, partially decayed and fitted out with bionic parts. Cyber-Zilla had all the strength he had when he was alive, as well as some new weapons, including atomic fire like his son. When Junior broke free of the aliens' control, he entered into battle with his cyborg father and was almost defeated. Junior managed to recover quickly thought, and was able to bring Cyber-Zilla down by ripping the wiring from his chest unit, shutting down the cyborg's life-support. With their greatest weapon defeated, the aliens had no option but to beat a hasty retreat.
Zilla was one of the monsters under the Xiliens' control and launched an offensive upon Sydney, Australia. When Godzilla was freed and pursuing the Gotengo battleship back to Tokyo, Zilla was dispatched back to Sydney to battle the King of the Monsters. He tried leaping at Godzilla, but to no avail: He was smashed into the Sydney Opera House and immediately wiped out by Godzilla's atomic breath, all within less than 30 seconds.