I am Legend, the classic horror/sci-fi novel by Richard Matheson, is one of my favorite books. It's just such a fascinating, rich human story.
Kimberly Rae and I watched The Last Man on Earth the other night, which remains the truest adaptation of the novel, although Vincent Price, who I love, is hopelessly miscast, despite a rather valiant effort at performing with a more hard-boiled persona than he usually takes on.
I was pleased to read this Interview with Richard Matheson on the subject of adapting it. He suggests Jack Palance as having been a good choice for the protagonist Robert Neville.
(Apparently, Palance would have gotten a lot more work if authors cast their own novels, as he was also Donald E. Westlake's choice to play Parker.)
When the recent adaptation, that became I am Legend by Francis Lawrence starring Will Smith, was being developed, I had favored Kurt Russell as my choice for Neville. I got a bit of flack from some other fans of the novel for this, so I was pleased that he was also Matheson's pick out of the rumored choices.
In discussing my various concerns with the structure as storytelling and as adaptation, I noted that I was somewhat frustrated with the ending, which tries to action up the ending, leaving Price's acting to cover a lot of the territory covered at the end of the novel.
Craig Blamer, who wrote I am Legend, which remains one of my favorite pieces discussing the novel and its relationship to movie adaption, noted that Matheson himself had made the ending more cheerful in the screenplay he worked on for Hammer Films, that was eventually re-written and made into The Last Man on Earth with Matheson deferring his credit to the pseudonym Logan Swanson.
I still haven't read that screenplay, although I note that it's now available in the affordable edition Visions Deferred: Richard Matheson's Censored I am Legend Screenplay and not just the amazing looking but prohibitively priced Bloodlines: Richard Matheson's Dracula, I am Legend And Other Vampire Stories. I may have to catch up on that soon.
In looking into this, I found this short movie of the story.
It's an interesting attempt to capture the ending, but frankly I don't find its changes particularly more satisfying than those in The Last Man on Earth, both of them clearly get the ending, but fall short of the emotional impact of it.