There is a strange irony in the fact that writers for TV and movies make a lot more money than do print writers but garner a lot less fame. Which irony is doubled when you consider that Richard Matheson was a print writer best known for his media work who was greatly admired by Ray Bradbury, a prolific media writer who is best known for his print work.
Matheson was an originary writer -- a source of ideas rather than a writer who takes other writers' ideas and casts them in better prose. Here's a case in point. One of his novels, I AM LEGEND, posited the last man on Earth who is under nightly siege by former humans turned vampire. This was a great idea which was obviously suited for a movie.
Which movie has been made I don't know how many times, possibly most famously as THE OMEGA MAN.
But there are movie geeks out there who can read me chapter and verse.
It doesn't stop there, though. At one point an obscure film maker named George Romera tried to get he rights to make his version of the novel and failed. So he tweaked a little here and there and came up with the first modern zombie movie.
An entire genre owes its existence to Matheson.
There'sa a lot more I could say, but the essence of it is that he was a writer who enriched your life. I can confidently state that without knowing who you are. Of how many writers can that be said?
You can read io9's excellent memorial here.