As of 2008, Dan makes $400,000 per episode of The Simpsons.
When Dan was a student teacher, he used to engage the children with his 'voices', and they were so impressed they said he ought to be in Hollywood - giving him pause to rethink his career.
In the summer of 2008, Dan appeared on stage in Broadway Bound, with JoBeth Williams and Jonathan Silverman.
Dan's favorite film is The Producers. His favorite TV show, past or present, is Taxi, and his favorite music is anything sang by The Beatles. His favorite book is The Book: On the Taboo Against Knowing Who You Are by Alan Watts.
Dan wrote the play The Purple Dawn, staged in Geneva College, Beaver Falls in Pennsylvania.
Dan's video game voice credits include Flux Wildly in Toonstruck, Homer Simpson, Grandpa Abe Simpson, and Barney Gumble in The Simpsons: Virtual Springfield, Earthworm Jim and Boogerman in Clayfighter 63 1/3, and Nordom in Planescape: Torment.
Dan is 5'10" (1.78 m) tall.
Dan's theatrical credits include The Alchemist, Where Did Vincent Van Gogh, Lost in Yonkers, Macbeth, Tom and Jerry, Catch 27, Cows on Ice, How Green Were My Values, Mirrors at the Border, Orwell That Ends Well, A Midsummer Night's Dream, and The Taming of the Shrew.
Sometimes screw-ups turn out to be good. In an episode of The Simpsons, it was scripted that Homer would sing "I am so smart, I am so smart, S-M-A-R-T". But when Dan read it, he screwed up and said "I am so smart, I am so smart, S-M-R-T I mean, S-M-A-R-T". The editors liked the change so much that they kept it in and it is in the episode to this day. The line also appears in the video games The Simpsons: Hit and Run and The Simpsons: Road Rage.
Dan won an Emmy in 1992 (Outstanding Voice-Over Performance) for The Simpsons' episode "Lisa's Pony". He won again in 1993 for the episode "Mr. Plow", in 2004 for "Today I Am A Clown" and for a fourth time in 2009 for the episode "Father Knows Worst".
Dan guest-voiced as himself in an episode of The Simpsons where he talked to Homer.
In one episode of The Simpsons, Fat Tony and his minions were discussing who to "whack". Some of the people they said they would kill were the members of the Castellaneta family.
Once asked in an interview what "D'oh!" means. He replied that he thought "D'oh!", the trademark line of his The Simpsons character Homer, was a euphemism for "damn".
Dan won an Annie Award in 2000 for playing the voice of the Postman in the TV movie Olive, the Other Reindeer.
Dan lent his voice for the TV commercials for Butterfinger bars, Office Depot (1998), Intel (1998), and Mastercard credit card (2004).
Dan appeared in the following albums: The Simpsons Sing the Blues in 1990, Fear and Loathing in Las Vegas in 1996, and The Simpsons Songs in the Key of Springfield in 1997.
He is a vegetarian, doesn't drink, and practices tai-chi.
Dan: (on his popular character from "The Simpsons") To many, Homer may appear lazy and a loser, but he's just much misguided. He's boorish, sure, but well meaning and, I guess, the one thing we have in common is the pursuit of lousy diets.
Dan: There are times when the writers ask us to improvise. Sometimes the animators are inspired by what you do, and sometimes you are inspired by what the animators do.
Dan: The Simpsons take up so little time that I'm able to do other things as well.
Dan: The Simpsons can go anywhere in the world and not worry about any budgetary issues. However, even when the show has had its run, I think the characters can go on in perpetuity.
Dan: The nice thing is that, at least in Los Angeles, I'm known as a character actor and I do auditions for other things besides just cartoon shows.
Dan: The humor is essentially dark for a cartoon and sophisticated. But at the same time, being a cartoon gives the writers more freedom than in a normal sitcom. It always pushes the line that, despite human failings, the Simpsons are really decent people.
Dan: (talking about "The Simpsons") One of my favorite episodes was the one in which Homer grew hair. That was a very unique episode, since there was a gay secretary, but that wasn't even the issue of the show-the issue was Homer's image changing because he had hair.
Dan: It's the weirdest thing. When you go into acting, you expect to be a huge star and to be recognized... It did happen, but not in the way you expect it to... In LA, I'm just another character actor.
Dan: It's the cushiest job, but some lines are so funny that I crack up.
Dan: It's hard to find a play that's right for me to do. Rather than waiting around for the right script to come along, I decided to write one myself.
Dan: It's a different way of getting across an emotion. You're trying to get it across to the animator because the animator is inspired by the voicetrack in terms of how to animate the character.
Dan: If I were actually Homer Simpson, I'd be getting scripts out the wazoo.
Dan: I think that most people don't even know that I do other things. They think that Homer is all that I do.
Dan: I always enjoyed writing. I did playlets in high school, I did radio shows in college. That's one of the reasons I went down to Second City, because you could do acting and writing.
Dan: After years of doing it, you learn the difference between your ego and your opinion. When you're married you have to cut through that.