But for as much trouble as Leon has caused others, he has been nothing but a boon to J. B. Smoove, the writer and performer who portrayed the character on the acerbic HBO sitcom. The role has been a vehicle for Mr. Smoove to reach an increasingly wider audience and an opportunity to stretch the boundaries of what his comedic alter egos can get away with.
“I definitely know there’s a difference between Leon and J. B.,” said Mr. Smoove (whose real name is Jerry Brooks) during a recent interview at his home in Woodland Hills, Calif. “But at times it’s very easy to be Leon. One thing about Leon, man, he never changes his mind about anything. He sees it how he sees it, in black and white.”
In person Mr. Smoove is a gentler jester, a 6-foot-2-inch comedian with a pliable face who describes himself, in the third person, as “so close to 40 he can smell it.”
Born in the small town of Plymouth, N.C., and raised in Mount Vernon, N.Y., he trained in the early 1990s at the Uptown Comedy Club, a Harlem institution, where he came under the tutelage of André and Kevin Brown, the brothers who founded the club. They taught him one hard and fast rule: Every comedian has to have his own character.
“You couldn’t steal jokes because you had your own style,” he explained. “I just always found it easier to be the same guy onstage as you are offstage.”
Reaching back to a short-lived previous career as a hip-hop dancer, when he and a partner performed under the names J. Groove and J. Smoove, he rechristened himself J. B. Smoove. His earliest bits drew on memories of an urban youth: sticky mousetraps, disobedient Slinky toys, sidewalk games and chants.
Though an opportunity to audition for the sketch comedy series “In Living Color” fizzled, Mr. Smoove nonetheless built a following as a versatile comic who could play to both black and white audiences.
“A lot of comedy is segregated, but there’s no real reason for it,” said the comedian and filmmaker Louis C. K., an early fan. “Black comedians are these hard-core dudes, and he’s just this wild goofball. And white comedians dismiss a huge amount of people. They just go, ‘Oh, he’s a black guy, so he’s going to be doing that black-guy stuff.’ ”
Mr. Smoove “doesn’t belong to a school of comedy,” he added. “A lot of people are either being campy or angry, and he’s just making you laugh.”
After appearing in Louis C. K.’s films “Tomorrow Night” and “Pootie Tang,” Mr. Smoove joined the writing staff of “Saturday Night Live” in 2003.
He spent three years there, but he could tell that his offbeat sketch ideas (what if Paris Hilton were a softball pitcher?) didn’t quite fit the show’s sensibility, and he was concerned that his occasional appearances were putting him in competition with full-time cast members.
“You can be aggressive and go for yours, or you just chill and let people shine,” he said. “I’ll get my shine later.”
Sure enough, after leaving “SNL” Mr. Smoove landed on “Curb Your Enthusiasm” (whose sixth season is scheduled for DVD release on Tuesday) as a hanger-on who joins members of his family, displaced by a hurricane, after they move in with Larry David and his wife. Soon Leon’s ungrammatical boasts (“I brings the ruckus to the ladies”; “That’s how I do’s it, Larry”) had become the season’s most memorable catchphrases.
With his urban patois and aggressive posturing — in one episode Leon literally steals the shirt off the back of a pedestrian because Mr. David believed the shirt was his — the character appeared to be one more element of a season designed to transgress as many racial taboos as possible. But the show’s creators deny that Leon was meant to serve deeper agendas.
“There are people, black and white, who would take the shirt off somebody and not think twice about it,” said Jeff Garlin, a co-star and executive producer of “Curb Your Enthusiasm.” “Our guy happened to be black. Does that mean all black people steal shirts? No. It’s not making a blanket statement about all people.”
Nor did fellow comedians detect any racial stereotyping in Mr. Smoove’s “Curb Your Enthusiasm” performance. “It’s not like they hired some great Shakespearean actor, and that’s how he chose to play it,” Chris Rock said. “That’s who J. B. is. I can’t fault a guy for being himself.”
Mr. Smoove has already parlayed the character into bigger opportunities. This month he agreed to an arrangement with Sony Pictures Television under which he would join the cast of the Fox sitcom “ ’Til Death,” or receive his own sitcom development deal if “ ’Til Death” does not return.
Still, one senses that he would still relish the opportunity to slide back into Leon’s sleeveless T-shirts at the earliest possible opportunity. “Sometimes you have to be a Leon,” he said. “If he thinks something, he’s going to say it,” he said. “It’s like he’s got controlled Tourette’s. In life, you need somebody like that.”