One major influence upon Matheson and others of the genre is the Mary Shelley novel, The Last Man, about an immune person surviving in a plague infested world.
Although Matheson calls the assailants in his novel "vampires" and their condition is transmitted through bacteria in the blood and garlic is a repellant to this strain of bacteria, they have little similarity to vampires as developed by John William Polidori and his successors, which came straight out of the gothic fiction tradition.
In I Am Legend, the "zombies" share more similarities with vampires, and the novel influenced the zombie genre and popularized the concept of a worldwide zombie apocalypse.[7]
Although the idea has now become commonplace, a scientific origin for vampirism or zombies was fairly original when written.[8]
According to Clasen:
"I Am Legend is the product of an anxious artistic mind working in an anxious cultural climate. However, it is also a playful take on an old archetype, the vampire (the reader is even treated to Neville’s reading and put-down of Bram Stoker's Dracula). Matheson goes to great lengths to rationalize or naturalize the vampire myth, transplanting the monster from the otherworldly realms of folklore and Victorian supernaturalism to the test tube of medical inquiry and rational causation. With I Am Legend, Matheson instituted the germ theory of vampirism, a take on the old archetype which has since been tackled by other writers (notably, Dan Simmons in Children of the Night from 1992)."
— Mathias Clasen[9]
Although referred to as "the first modern vampire novel", it is as a novel of social theme that I Am Legend made a lasting impression on the cinematic zombie genre, by way of director George A. Romero, who acknowledged its influence and that of its original cinematic adaptation, The Last Man on Earth (1964), upon his seminal film Night of the Living Dead (1968).[10][7][11][12][13]
Discussing the creation of Night of the Living Dead, Romero remarked:
"I had written a short story, which I basically had ripped off from a Richard Matheson novel called I Am Legend."
— George Romero[14]
Moreover, film critics have noted similarities between Night of the Living Dead (1968) and The Last Man on Earth (1964).[15]
Stephen King said: "Books like I Am Legend were an inspiration to me."[16] Film critics noted that the British film 28 Days Later (2002) and its sequel 28 Weeks Later both feature a rabies-type plague ravaging Great Britain, analogous to I Am Legend.[17]
Tim Cain, the producer, lead programmer and one of the main designers of the 1997 computer game Fallout cited I Am Legend and the movie The Omega Man as influences on the game:
"This book was how a[n] individual would handle thinking that he was the last survivor on Earth. This is why in Fallout 1 when you're voted to leave the Vault, we really wanted that sense of isolationism; that sense of: You are the only person out here on the Wasteland who is, quote, 'a normal person', and we wanted you to feel, like, special in that way."[18]
The Doctor Who episode "Asylum of the Daleks" sees Oswin Oswald introduced in a similar fashion to Neville as an homage to the novel, with both Oswin and Neville checking defences, boarding up the door/window, listening to classical music, and turning it up to drown out the sound of the enemies outside (Daleks for Oswin, vampires for Neville).
