Although “in movies” is part of the title, I suspect that the really distinctive voices are those in TV and radio we rarely (if ever) see the faces for.
Think about that voiceover guy with the catchphrase “In a world…”
Don Pardo
Johnny Gilbert
Shadoe Stevens
Ed McMahon
Billy Mays!
Adam West.
I’ll add John Wayne and Fran Drescher.
What??!!! This thread is already 3 hours old and no one has said Morgan Freeman?!!!
Andy Devine!
ETA: RONALD COLMAN!
What about all those narrators on PBS? Many of those distinctive voices are of people I don’t even know the names for. But their voices are so distinctive.
One I do know the name (and face) for is David McCullough (II) but there are so many others on NOVA and Nature and other documentaries whose voices are omnipresent on shows on PBS and Discovery and the like.
And the voiceover folks on commercials? It’s fun to identify people on commercials by just their voices. Lately “Dexter” (Michael C. Hall) is the voice in at least one car commercial.
Liev Schreiber
James Garner
Dennis Hopper
The late Don LaFontaine.
Mary Wickes
In a world where there are movie trailers. There was only one Don LaFontaine
Damn. Was enjoying watching the youtube link for too long 
That’s the one. I knew there was a Fontaine in there, but I confused him with Frank Fontaine who was Jackie Gleason’s singing bartender Crazy Guggenheim.
Jonathan Winters
Dave Gardner
Andy Griffith
Don Knotts
Jim Nabors
Y’all want to get a thread going on those people whose voices sound enough alike to be confused for each other?
I was once listening to an old Andy Griffith show and THAT VOICE came on. I looked up to see a very, very, very young JACK NICHOLSON.
Bobcat Goldthwait.
Samuel L. Jackson(particularly when yelling, which is mostly what he does anyway).
Danny Devito
Well, then, Marjorie Main.
George Clooney is the very first name that popped into mind.
Morgan Freeman (who has already been noted) and Demi Moore. Her voice is kind of raspy and I always immediately recognize it.
Morgan Freeman was also my first “instant recognition” choice.
Patrick Warburton
Alan Rickman!