Christopher Hitchens.
Definitely concur on this one, I miss reading Christopher Hitchens’ columns.
I would add Graham Chapman to the mix, thought of that as I was watching Eric Idle sing some Monty Python tunes at the Olympics closing ceremonies.
I miss Ed Bradley. 60 Minutes just hasn’t been the same since he’s been gone.
Also, whenever I happen to catch Diane Sawyer on the evening news, I realize how much I miss Peter Jennings.
He lived to be fairly old, 84. And he suffered from depression. So I hate to be selfish and wish he had lived even longer. But we could use a few more books by Kurt Vonnegut.
One of the first that came to mind. Under-appreciated in the light of guys like Belushi/etc who she could go stride for stride with, and unlike many (most?) comedians in the so-called modern era, could be funny without being nasty, vulgar etc. Remember those days?
Carlin was so sharp and did some incredible stuff, but his “angry man” and political rants at the end got old.
Another outstanding and far too often overlooked choice. Guy was brilliant IMO.
I’ll add Walter Cronkite. The news media need integrity beyond words.
Dean Martin was another great choice as was Johnny Carson. ah the greats.
Musically, Buddy Holly and Jim Croce. Holly especially - he could have continued to profoundly influence rock. On a more “minor” note the Caldwell brothers (of Marshall Tucker fame).
I was going to say Johnny Cash but he seemed like he was ready to go, he wasn’t in great health at the end. Still sad that he’s gone, he died the same day as my grandfather.
Phil Hartman. Thinking about still makes me want to kick something.
I agree. I had the flu, was sleeping on my couch, and woke up in a NyQuil hangover to this news. I hoped I was hallucinating.
John Ritter’s death almost made me cry. I still miss him, too.
Oh, yes. This. Poor Mitch.
I also wish we’d seen how much more Nirvana had to offer. Kurt Cobain. 
Several already named here, and add Ray Charles. That man was a national treasure.
Steve Irwin. Dammit. (Crikey?) Seriously, the wannabe zoologist in me still chokes up thinking about it.
Others mentioned that I will add a “Hear, hear!” to:
Phil Hartman
Madeleine Kahn (which makes me think to add Gilda Radner)
Johnny Carson
and the OP’s George Carlin.
William Windom, who just passed away at the age of 88.
I was just thinking about Carlin when i heard they might make a Bill and Ted sequel and that both Keanu and Alex Martins are going to star. It just won’t be the same without Rufus though.
Steve Jobs.
Jim Henson.
Eric Woolfson (Alan Parsons’ partner in the Project)
Steve Allen.
I see no one has mentioned Gene Roddenberry yet. He created characters that still resonate with us today. Kirk. Spock. Bones. Scotty. And an entire universe of possibilities that still inspires people after more than 45 years.
And along with him I’ll miss DeForest Kelley and James Doohan.
George must be glad he’s dead. The state of the nation at present would surely render him incapable of doing much besides writhing in a heap screaming BLOW IT OUT YER ASS! BLOW IT OUT YER ASS!! BLOW IT OUT YER ASS!!!
Michael Crichton. He was almost like a Hitchens who could write good stories.