Rollin' With Dad.(The Talk of the Town)(Doug Ellin)

One entrance is pretty much as cool as another when you're visiting outer space. So it came as a surprise that Doug Ellin, the creator of "Entourage," the HBO series, based partly on his experiences, about a posse of young friends making the Hollywood scene, chose to spend a recent afternoon at the Hayden Planetarium, where the door policy is lax and strollers outnumber black Escalades.

"Luc, you want to go in there and see the big elephants?" Ellin asked his five-year-old son, before setting off for the Hall of African Mammals, in the American Museum of Natural History. (The space show wasn't due to start for another hour.)

Ellin was in town for his father's seventy-fifth birthday. Born in Brooklyn, like his parents, he was brought up in Merrick, Long Island--for Ellin, a knockaround paradise of pizza and pickup basketball where, he said, "you'd have a dentist living next door to a mobster." While he was in college, at Tulane, Ellin saw a picture of a pretty girl pinned to a friend's bulletin board and demanded her number. It began with 213--California--and he moved there after graduating. The girl, Melissa, picked him up at the airport. They have been together ever since, and, along with Luc, they have a young daughter. According to Ellin, "something very mellow, maybe dinner and home by eleven" is their idea of a fun Saturday night.

Still, for an avowed family man, Ellin retains an air of up-for-whatever breeziness. He arrived at the museum remarkably free of kid paraphernalia. He let Luc drink out of a stranger's water bottle. For a writer, he did not seem particularly enamored of words. "It was really a function of the least amount of work," he said, of majoring in English. Asked how he comes up with ideas for the show, he said, "I really do no research. I hang around people, listen." Dressed optimistically--he is not a habitual checker of weather reports--in a striped buttondown (tails out), jeans, and white throwback sneakers, he yelled, "Yo, Luc, check this out!" as they sailed past Birds of Japan.

Ellin's boyish dodges may bring to mind Vince, "Entourage"'s protagonist, ...