John Barrowman

Hold out for a hero no longer: Captain Jack is back. In the fourth season of Torchwood, now playing on Starz, John Barrowman has returned as sci-fi's only immortal omnisexual space-time traveler. And the headline? 'Jack's a big old gay in this one,' says Barrowman. 'I'm naked, having full-on man-to-man sex with somebody. More than one! I'm really pleased we get to explore his gay side.'

No complaints. And not really shocking, considering the series has moved from BBC America to the network that brought us the world of Spartacus: Gods of the Arena, where full-frontal male nudity was practically a requirement. It's a welcome shift from last season's kind-of-a-bummer finale, which saw Jack lose two members of his team and his boyfriend, Ianto. In the new season, a cosmic event has caused the human race to stop dying, which results in some personal-space issues, not to mention, says Barrowman, that 'if your head gets ripped off in a car accident, you're still alive.' Jack syncs up with a new investigative team that includes Six Feet Under's Lauren Ambrose, ER's Mekhi Phifer, and Bill Pullman, who plays Oswald, a semi-relatable pedophile. 'We're touching on subject matter that no other TV shows will,' says Barrowman. 'You're going to like Oswald, but be pissed at yourself for liking him.'

Jack's romantic exploits have always been a publicity flashpoint for the show. He made his first big splash after a lip-lock with Christopher Eccleston's Doctor Who; now, YouTube is rife with video compilations of Barrowman's snogging scenes. This season promises to add subtext to the sex. 'We go back into the past and meet a young man,' says Barrowman. 'You see how Jack becomes who he is. This is how he fell in love way back in history. It gives us a look into what his relationship with Ianto was. It's beautiful, and I'm really proud of it.' The decision was a token of gratitude from series creator Russell T. Davies. 'Russell basically said, 'This is a gift to you as an actor'you deserve this kind of story,' ' says Barrowman. 'It was a great day. When I left for work that day my partner said, 'Why are you so cheery?' I said, 'Oh, no reason, really. I just get to have sex with a hot 20-year-old.' '

The day before we speak, reports surface that a proposed new Star Trek TV series would feature a gay character, a development that might have been unimaginable before Torchwood. Does Barrowman consider himself a pioneer? 'I don't know if I am,' he says. 'People connect with Torchwood. We represent people who are actually out there in society. Our community is diverse. Maybe Jack was a groundbreaker in that we were representing a different part of the gay community, other than people who are camp and over-the-top.'

One of the first comfortably out actors of his generation, Barrowman maintains a happy union with the British architect Scott Gill. The two have been together since 1993 and entered into a U.K. civil partnership in 2006. 'Before we did our civil partnership, we said it wouldn't change us,' Barrowman says. 'But the day we did it, it did change us for the better. It was a weird but really good feeling. I'd like to be part of the movement to bring that over here in the U.S.'

Although a rumored Glee appearance hasn't materialized, Barrowman is working with his sister to adapt Torchwood into a series of young-adult novels that he hopes to translate to the big screen. Meanwhile, he hosts the weekly live-performance and wish-fulfillment TV show Tonight's the Night, a hit in Europe that he also hopes to bring to America. So does he have his sights set on becoming the next Simon Cowell? 'Oh, no -- Simon's bigger,' says Barrowman. 'Well, in the TV world.'

The fourth season of Torchwood airs Fridays at 10 p.m. EST on Starz.