From an interview on Conan O’Brien:

Conan: You have this image right now, of an action star, tough guy, but there is, for lack of a better term, maybe a slightly nerdy side to Vin Diesel, is that fair to say?

audience: *laughs*

Conan: Please don’t rip my head off, reach into my neck, and pull my heart out, but… You can do that later, but.., let’s just say a side of you that people might not expect.

VIN: I spent a lot of years playing a game called Dungeons and Dragons.

audience: *laughs*

VIN: Very few people know that I was rolling 20-sided dice and talking like a half-orc

Conan: You would talk in the voice when you played the game?

VIN: Oh, we completely role-played, yea.

Conan: *laughs* you’re kidding?!

VIN: (in the voice of a half-orc) “How dare you!?”

Conan: That’s amazing! (in a nerdy voice) “Fear not, Gandalf is on the way!”

audience: *laughs*

Conan: That’s what I would be, if I was playing with you. You would not let me play with you, probably. You’d be like “that guy’s too nerdy, he’s gotta go.”

audience: *laughs*

Conan: So you played this for like how long?

VIN: For like 24 years.

Conan: For 24 years?! *laughs* I know…

audience: *laughs*

VIN: Now I call it the training ground for imagination.

Conan: Right, well that’s very…

VIN: But this was before video games. I started playing in the 70s. And, this was, I mean, I could have played Risk, Monopoly, or D&D.

Conan: Right, which was probably the cooler of those games.

VIN: I think, yea.

Conan: And you created a character for youself, didn’t you?

VIN: I created a character… No one knows this, but in Triple-X, one of the tattoos, right above my belly-button, or below my belly button, I don’t know why I’m saying this *hoots from audience*, was the name Melkor. And that came from a character that I had, uh..

Conan: That you created in Dungeons and Dragons?

VIN: that I created. That was a Drow witch-hunter. Double-specialized witch-hunter. but this is all

Conan: There are so many nerds watching right now who are just thrilled. Cause you’re making them
cool, suddenly. All these guys are watching going “Go, Vin Diesel, Go! Go!” All hail, Melkor, you know?

audience: *applause and laughter*

Conan: I think that’s neat though. See that you did, see that you’ll talk about it.