“I Am Legend” has been made into 3 or more movies, none of which have anything like the book’s ending.
The Last Man on Earth (1964) is dull and misses the point almost entirely, but almost manages the title line. Not quite.
The Omega Man (1971) is exciting and misses the point even further.
I Am Legend (2007) almost gets it. The vampires are competent. Will Smith’s smarter than Neville of the book, but crazier. But then both endings fail to treat the vampires as a society.