Will President Frank Underwood sleep with the fishes in Netflix’s “House of Cards” next season?

While far from a spoiler alert, the idea was raised last week by at least one media-watcher after the series’ star, Kevin Spacey, agreed to head Relativity Media’s movie division.

Albert Fried analyst Rich Tullo told my colleague Richard Morgan that he thinks the only reason Spacey would agree to work for a studio that is a rival to Netflix is that he is upset about CEO Reed Hastings’ streaming service.

There are a couple of reasons Spacey would be angry, according to Tullo. First, Spacey makes $15 million per season but thinks he deserves a lot more, given the role “House of Cards” has played in turning Netflix into a video-streaming enterprise valued at $40 billion — or so the theory goes.

Second — and this is where Tullo goes all crystal ball on us — Spacey could be riled because Netflix kills his character in Season 4, which starts March 4.

As reported, Netflix’s was the last creditor objection to Relativity’s plan of reorganization.

“It is odd to find Spacey on the opposite side of Netflix in a legal controversy having to do Relativity Media’s bankruptcy,” Tullo told The Post. “That says to me Spacey believes his future with Netflix is short-term, meaning it shouldn’t be surprising if Underwood gets killed off in Season 4.”

Spacey’s camp believes Tullo’s theory is ridiculous and hurtful, sources close to the actor said.