The 42-year-old movie hunk and the 26-year-old brunette happily declared this week that they were "dating," with the notoriously private Cruise eagerly posing for pictures with Holmes as they emerged from a limo in Rome.
But some folks in the know believe the sudden romance may be little more than a carefully orchestrated publicity stunt — created to drum up press for the pair, both of whom just happen to have movies coming out in June.
"This definitely looks like a setup for promotional purposes. It's a romance made in p.r. heaven," said Linda Mann, president of Mann Media, a Manhattan p.r. firm. "It'll last until the box office dies down."
Neither Tom nor Katie's reps returned calls yesterday regarding the publicity-stunt claim.
But Katie clearly seemed to be gunning for the "Top Gun" star last October when she told Seventeen magazine, "I think every little girl dreams about [her wedding]. I used to think I was going to marry Tom Cruise."
Her lawyer dad, Martin Holmes, insisted to "Access Hollywood" that the sparks are real.
"I'm happy and excited for Katie. She has a good head on her shoulders, and we trust her judgment," he said.
But a Post survey of people around Manhattan's Rockefeller Center found plenty of skeptics.
"I think it's a joke. He's way too old — and she's way too young and hot to be going out with him," said Mike Villa, 28.
Jessica Sanchez, 20, said: "I was shocked. I couldn't believe it. I was like, 'Katie Holmes and Tom Cruise!?' It could be a publicity stunt."
Others said that with a 16-year age difference, the couple may not be age appropriate, but at least they're close to height appropriate. The "Dawson's Creek" cutie stands 5-foot-8, only 1 inch taller than Cruise, who when he was married looked less than towering compared to the 5-foot-10 Nicole Kidman.
Both stars have had bad luck in the love department. Both of Cruise's marriages, to Kidman and Mimi Rogers, ended in divorce. Holmes and actor Chris Klein recently called off their engagement.