Venerable author Richard Matheson has withheld his stamp of approval from his 1954 plague novel's screen adaptations, ''The Last Man on Earth'' and ''The Omega Man.'' And somehow one doesn't picture him warming to a comics version, either. But the retelling crafted by writer Steve Niles (''30 Days of Night'') and artist Elman Brown actually stays utterly faithful to its source. Matheson's musings on the awfulness of isolation are transferred intact, but so are some unfortunately static -- and lengthy -- passages on the science of disease. Still, ''Legend'' is worth buying just for the full-page image of the hero's dead-and-buried wife showing up at the door for a bloodthirsty booty call.