Kirk55555, you're not alone. Everyone knows Matheson's work, but, sadly, not everyone knows his name. He was possibly the most influential science fiction/horror writer in America who wasn't a household name.
Among other things, he was the grandfather of the entire zombie apocalypse genre. His 1954 novel, I Am Legend,
inspired Romero's Night of the Living Dead,
which led to The Walking Dead
and every other variation on the theme. And, of course, he wrote many of the most famous episodes of The Twilight Zone.