I did some research into voice actors after finding the same names coming up again and again on my favourite toons. Names that I realized that for most people had no face to them. So, as a service to you, the billions of people who will never read this, I have compiled a list of some of the most prolific voice actors in the biz.
 Pamela Segall Adlon >
Pamela Segall Adlon > - Currently the voice of Bobby Hill, but has also voiced Milo Oblong (
The Oblongs) and Spinelli on 
Recess.
Hank Azaria - Mostly known for his 
Simpsons work as Apu, Moe, Chief Wiggum, Carl and others. Has also been Harold Zoid on 
Futurama and Bartok the bat on 
Anastasia.
Mel Blanc - He basically invented voice acting, as the man behind Bugs Bunny, Daffy Duck, Porky Pig, Yosemite Sam, Tweety and Sylvester. He also played Barney Rubble and Dino on 
The Flintstones as well as Mr. Spacely on 
The Jetsons.
 Daws Butler <
Daws Butler < - What Mel Blanc was to the 
Looney Tunes, Daws Butler was to Hanna-Barbara, voicing Yogi Bear, Huckleberry Hound, Snagglepuss, Quick Draw McGraw, Augie Doggie, Wally Gator and Elroy Jetson.
Nancy Cartwright - The long-time voice of Bart Simpson also does Rufus the Molerat on 
Kim Possible, Chuckie Finster on 
Rugrats, Pistol on 
Goof Troop, and the ill-fated Toon Shoe on 
Who Framed Roger Rabbit? Dan Castelleneta >
Dan Castelleneta > - Besides his work as Homer and Grandpa Simpson, as well as many other characters on the show, Dan has voiced the Genie on the 
Aladdin series, 
Futurama's Robot Devil, and 
Darkwing Duck's nemesis Megavolt.
Townsend Coleman - Played Michaelangelo the 
Ninja Turtle, Wayne Gretzky on 
ProStars and was the title character on 
The Tick and 
Where's Waldo? Jim Cummings <
Jim Cummings < - One of Disney's go-to guys from the mid-80's. He is the current voice of Winnie the Pooh and Tigger, and has played Don Karnage (
TaleSpin), Monterey Jack (
Rescue Rangers), Bonkers and Lucky Piquel (
Bonkers), Darkwing Duck, Zummi (
Gummi Bears), Pete (
Goof Troop), and Ed the Hyena (
Lion King).
Mike Judge - The former voice of 
Beavis and Butthead, can now be heard as Hank Hill and Boomhauer on 
King of the Hill.
Tom Kenny - Plays the title character on 
SpongeBob SquarePants as well as the Mayor on 
Powerpuff Girls, Ratbert on 
Dilbert, The Penguin on the latest version of 
Batman, Spyro the Dragon, and Heffer on 
Rocko's Modern Life.
 Maurice LaMarche >
Maurice LaMarche > - Perhaps best known as The Brain from 
Animaniacs, he has also voiced Kiff Kroker from 
Futurama, Garbage Man from 
Dilbert, Chief Quimby from 
Inspector Gadget, Dizzy Devil from 
Tiny Toon Adventures and does the voice of Toucan Sam for 
Froot Loops.
Phil Lamarr - A 
MadTV alumnus, he has been the voice of 
Samurai Jack, Hermes Conrad (
Futurama) and Green Lantern (
Justice League).
Seth MacFarlane - The brains and voices behind 
Family Guy (Peter, Stewie and Brian Griffin; Quagmire) and 
American Dad (Stan Smith, Klaus and Roger).
 Tress MacNeille <
Tress MacNeille < - A real workhorse in the industry, she has voiced Dot Warner (
Animaniacs), Chip and Gadget (
Rescue Rangers), Carol (
Dilbert), Morbo's co-anchor Linda (
Futurama), Daisy Duck, Charlotte Pickles (
Rugrats), Agnes Skinner (
Simpsons) and Babs Bunny (
Tiny Toon Adventures).
Don Messick - The partner to Daws Butler, he played many roles for Hanna-Barbara over the years, including Scooby-Doo, Boo Boo Bear, Bamm-Bamm Rubble, Astro Jetson and Dr. Quest, as well as Papa Smurf.
Frank Oz - Another one-man vocal menagerie, he voiced many of the Muppets, including Bert, Grover, Fozzie, Miss Piggy, Cookie Monster and Animal. He also provides the voice of Yoda.
 Rob Paulson >
Rob Paulson > - Best recognized for his work as Yakko Warner and Pinky on 
Animaniacs, he has also played PJ on 
Goof Troop, Spike in the 
Land Before Time series, Raphael the 
Ninja Turtle, and Arthur, sidekick to 
The Tick.
Kath Soucie - Played the DeVille twins, Phil and Lil, on 
Rugrats, Linka on 
Captain Planet, and Kanga in all the current Pooh productions.
Cree Summer - Currently voicing Foxxy Love on 
Drawn Together, she has also been Penny on 
Inspector Gadget, Elmyra on 
Tiny Toon Adventures, Susie on 
Rugrats, Princess Kida on the 
Atlantis movies and the Green M&M.
Patrick Warburton - Most often heard as Joe Swanson on 
Family Guy, he has also been Buzz Lightyear on the TV series, Kronk on 
The Emperor's New Groove, Brock Samson on 
The Venture Bros and the Wolf in 
Hoodwinked.
 Frank Welker <
Frank Welker < - A king among voice actors. Usually voices animals who communicate by noises, like Curious George, Santa's Little Helper (
Simpsons), Abu (
Aladdin), Bronx (
Gargoyles), Nibbler (
Futurama), Brain (
Inspector Gadget), the cricket from 
Mulan, the hummingbird from 
Pocahontas, the dolphin from 
seaQuest, and the monkey from 
Captain Planet. He also does Fred from 
Scooby-Doo, a bunch of 
Smurfs, Megatron from the 
Transformers movie and Dr. Claw (
Inspector Gadget).
 Billy West >
Billy West > - The current voice of Bugs Bunny and Elmer Fudd, he has also voiced Fry and Dr. Zoidberg from 
Futurama, Ren and Stimpy, Doug Funnie from 
Doug, Anita Bidet from 
The Oblongs, and in commercial campaigns as the Honey Nut Cheerios Bee and the Red M&M.
That's a sampling of some of the ones that make an impact on me, personally. Let me know if you have any other major additions to this list.