A model and actor was badly disfigured and fighting for his life after catching fire when he climbed atop a Manhattan-bound Metro-North train on Sunday, law enforcement sources said.

A train crew found Brian McClellen, 21, on fire on the roof of the New Haven line train shortly before 5:10 a.m. in Riverside, Conn., an MTA spokesman said.

The train, which runs on overhead electrical wires, had lost power. The workers had gone up to find out why.

Video taken at the Stamford rail station shows an apparently intoxicated McClellen climbing on top of the train, a source said.

Investigators believe the victim, who lives near Union Square, was burned after coming in contact with the train’s pantograph, which collects power from the 12,500 volts in the wires.

The crew used an extinguisher to put out the flames atop the sixth car.

McClellen was taken to Westchester Medical Center with electrical burns, some third-degree, on more than 90 percent of his body.

Cops did not know why McClellen, originally from Ohio, had climbed up.

His family described him as determined and talented.

“He’s a very good kid,” his uncle, James McClellen, told The Post by phone. “He grew up here in Ohio and went to New York with dreams of becoming an actor.”

Posts on Brian McClellen’s Facebook page indicate he may be a daredevil. It shows video of him doing backflips off roofs and apparently leaping off a small bridge into water. Photos show him playing on abandoned train tracks with his sister in August.

McClellen was in critical condition Sunday night after several surgeries.

Sources said he was intubated and sedated.

He was wrapped head to toe in bandages, and hospital sources said he was horribly disfigured.

Only his eyes were left exposed, with the skin around them purple and red.

McClellen’s agent, Ryan Colby, told The Post the actor had been booked last week for both a TV show titled “Younger’’ with Hilary Duff and for a Pierce Brosnan movie titled “Urge.”

He picked “Younger” and was set to begin work next week, Colby said.

“He’s a great guy,” Colby said. “He’s an energetic kid. Acting is all he wants to do.”

McClellen’s Facebook page has many happy posts, including updates on a trip to Las Vegas, attending a “Live! With Kelly and Michael” taping, and taking the Ice Bucket Challenge for the ALS Association.

In a post last year, he wrote: “I know im going to change the world. its only a matter of time.”