Penn Jillette was born on March 5, 1955 in Greenfield, Massachusetts. He is the big (6'6"), loud, blustery member of the comedy/magic duo Penn and Teller. As the running joke in their cult movie Penn and Teller Get Killed (1989) goes, he's the "big one with the hair and the fingernail" (see below).

Calling themselves "ripoff artistes" and relishing being referred to as "the bad boys of magic," the two put on a show that is a blend of illusion, sleight-of-hand, and very dark comedy, often involving what appears to be the death of one of them (usually Teller). Using plenty of stage blood, dangerous instruments (knives, needles, razor blades, guns), and even insects and worms (they once dumped five hundred cockroaches on David Letterman's desk during an appearance), they put on a show that is not only disgusting, but also funny and entertaining. On occasion, they'll reveal how some of the simpler tricks are done. (The pair have written some books that include how-to stuff on some of their tricks as well as new ones and essays on magic.)

Unlike Teller, who usually remains in his character as a non-speaker, Penn has a considerably longer list of television and movie credits (though they both share several, including a guest appearance on the Simpsons and several episodes of The Drew Carey Show as attorneys "Archibald Fenn" and "Geller").

A few roles:

Trivia:

Like his partner Teller, Penn doesn't touch drugs or alcohol (though they will use cigarettes in the course of their act but only for that reason), is an atheist, and a skeptic. They are good friends with well-known skeptic and former magician James Randi who makes a cameo in their 1989 film and all three are on the editorial board at the Skeptic magazine.

He wasn't much involved with magic until he met Teller, though he practiced juggling from a young age (later working for a time juggling on the New Jersey boardwalk).

He graduated from Greenfield high school in 1973 and attended Ringling Bros. and Barnum & Bailey Clown College.

The "fingernail" (he has his left ring fingernail painted red):
(quoted from their site)

There are three common answers to this question.
1) It means he once shot a man for asking personal questions
2) When Penn first began performing, his mother told him to get a manicure because people would be looking at his hands. In response to this, Penn had all of his nails painted red as a joke. The one remaining red fingernail is in honor of his dear mother.
3) The red fingernail provides excellent misdirection and is just plain cool.

some info provided from their website at www.sincity.com and The Internet Movie Database