Don't count out the ghost of Billy Thomas on Fox's Ally McBeal just yet: The specter's portrayer, Gil Bellows, tells TV Guide Online that being employed at another network won't preclude him from haunting his former flame should the need arise. "If there's a special reason, I would go back," says the actor, whose CBS drama, The Agency, debuts tonight at 10 pm/ET. "But it would have to be a special reason."

The last time Ally producer David E. Kelley called on Bellows to resurrect Billy was in the spring, when the character was to provide "counsel" to Calista Flockhart prior to her wedding to Robert Downey Jr.'s Larry. And although Downey's arrest forced Kelley to scrap the nuptial plot and replace it with an "Ally Goes to the Prom with her Teenage Client" story, Bellows still appeared in the episode — but more out of obligation than desire.

"Had I [initially] been given that script, I don't know that I would have come back," he says of the reworked installment, in which Billy gives Ally a pre-dance pep talk. "I feel like we [already] had wrapped it up beautifully."

Bellows is hopeful that Ally devotees follow him to his new CIA thriller, The Agency (which, in the wake of the Sept. 11 terrorist attacks, also has undergone some last-minute tinkering). And should the dramedy's fans have trouble seeing him as anyone other than Billy, the Canadian-born thesp takes that as a compliment.

"If they can't [forget about Billy], it means that I made an indelible impression," he points out. "At some point, you hope that you have a definitive role. But in my mind, I don't think it's Billy."