Technically, none. It has always been either a person in a very elaborate costume (as in all the Japanese Gojira films) or a computer-generated image (as in the American-made Godzilla film).
But if you're asking what lizard Godzilla is modeled after, the original Japanese Godzilla was a cross between a Tyrannosaurus Rex and a Stegosaurus (I believe the designers have gone on record saying this), and the US Godzilla looks to me to be basically a marine iguana with Jay Leno's chin added.
A Monster.
Godzilla
The Gila monster is the only poisonous lizard
Konodo Dragon, Water Monitor, Savannah monitor, Gila monster, beaded lizard, and Tree Monitor.
Gila monster
A male Gila monster is called a bull. There are only two venomous lizards in the world and the Gila monster is one of them. The other is the bearded lizard.
Monster X never appeared in Godzilla Unleashed.
the new monster is monster x Monster X came out in 2005 in Godzilla Final Wars.
Godzilla
Godzilla is smart for a lizard. She can comprehend traps and human behavior.
godzilla earth (2017) or thermonuclear godzilla (2019)
Godzilla will fight Deathla , a monster similar to his enemy Hedorah.
Since Godzilla is a fictitious creature we can't be certain of its biological status, but it certainly does resemble a huge lizard. Perhaps dinosaur would be closer.
yes Godzilla is a lizard because a experiment bomb turned into mounters
If Godzilla was real then he would be in the vertebrates and would be in the lizard family
The duration of Godzilla vs. the Sea Monster is 1.45 hours.
a giant lizard
yes, you see Godzilla started off as a normal lizard with a normal lizard family. but then they started nuclear testing on the island he inhabited. it killed almost all life but little Godzilla lizard was far enough not to affected by the blast. however the radiation from afterward mutated him and turned him into the beast we all love today