The Lizard (Dr. Curtis "Curt" Connors) is a fictional character, a supervillain in the Marvel Comics Universe. He is an enemy of Spider-Man. The Lizard first appeared in The Amazing Spider-Man #6 (November 1963), and was created by Stan Lee and Steve Ditko. In 2009, the Lizard was named IGN's 62nd Greatest Comic Villain of All Time.

Curtis Connors was born in Coral Gables, Florida. He was a gifted surgeon who enlisted in the U.S. Army and was sent off to war. He performed emergency battlefield surgery on wounded GIs, but his right arm was injured in a blast and had to be amputated. After his return to civilian life as a research technologist, Connors became obsessed with uncovering the secrets of reptilian limb regeneration and studied reptilian biology extensively. Working from his home in the Florida Everglades with the help of war buddy Ted Sallis, he finally developed an experimental serum taken from reptilian DNA. He successfully regrew the missing limb of a rabbit and then, despite the warnings of his wife Martha, chose to test it on himself. Connors ingested the formula and his missing arm did indeed grow back. The formula had a side effect; Connors was subsequently transformed into a reptilian humanoid monster. Spider-Man discovered this situation during a trip to Florida to investigate newspaper reports of the Lizard after the Bugle challenged him. Spider-Man was then able to use Connors' notes to create an antidote to restore him to his human form and mentality. Another attempt to develop this serum for safe use again resulted in Connors transforming into the Lizard, but on this occasion he was saved thanks to his former colleague Professor Charles Xavier and his first team of X-Men, Beast and Angel tracking the Lizard down in the swamps so that Iceman could send him into hibernation long enough to develop a cure.

Lizards are a widespread group of squamate reptiles, with more than 5600 species , ranging across all continents except Antarctica as well as most oceanic island chains. The group, traditionally recognized as the suborder Lacertilia, is defined as all extant members of the Lepidosauria (reptiles with overlapping scales), which are neither sphenodonts (i.e., tuatara) nor snakes – they form an evolutionary grade. While the snakes are recognized as falling phylogenetically within the Toxicofera clade from which they evolved, the Sphenodonts are the sister group to the Squamates, the larger monophyletic group, which includes both the lizards and the snakes.

Lizards typically have feet and external ears, while snakes lack both of these characteristics. However, because they are defined negatively as excluding snakes, lizards have no unique distinguishing characteristic as a group. Lizards and snakes share a movable quadrate bone, distinguishing them from the sphenodonts, which have a more primitive and solid diapsid skull. Many lizards can detach their tails to escape from predators, an act called autotomy, but this ability is not shared by all lizards. Vision, including color vision, is particularly well developed in most lizards, and most communicate with body language or bright colors on their bodies as well as with pheromones.