The grinning maniac charged with fatally shoving a 76-year-old retired teacher down Manhattan subway stairs was once a talented Broadway dancer who fell off the deep end during the pandemic, a pal told The Post.

Rhamell Burke, 32, posed for pics with movie stars and was in the cast of the megaflop “King Kong” on Broadway — years before police said he randomly pushed beloved ex-educator Ross Falzone down a flight of stairs at a Chelsea subway station last week, the friend said.

In one undated photo, Burke is seen at Lincoln Center posing with veteran actress Patricia Clarkson, whose credits include the hit HBO series “Six Feet Under,” and flicks such as “Shutter Island,” “The Green Mile” and “Jumanji” — and an Oscar-nominated performance for 2003’s “Pieces of April.”

Burke, reportedly a Long Island University grad, was part of the ensemble for “King Kong” in 2018 and 2019 under the stage name Rhamell Burke-Missouri, according to the Internet Broadway Database.

The pal said the suspect’s downfall appeared to start during COVID.

Deeply disturbing surveillance footage of Thursday’s vicious assault shows Falzone calmly walking into the 18th Street subway station around 3:30 p.m. when his attacker walks up behind him and shoves him with both hands down the concrete stairs without warning.

The helpless victim disappears into the lights at the bottom of the stairs as his attacker casually strolls away, and even signals for traffic to stop as he crossed the street and disappears into the night.

Falzone was rushed to Bellevue Hospital, where he was pronounced dead from a head injury.

“Ross was a dear, gentle man who enjoyed a career as a social worker for special needs children,” a friend of the victim said Sunday.

“At an early age he suffered heart issues, so he ate healthy food and stayed in lean shape, only to be killed by a man he could have helped.”

Burke was in court just five hours after the shove on an earlier assault case but initially walked away when no one recognized him as the shoving suspect — despite exhibiting bizarre behavior at the hearing.

Police later spotted Burke at Penn Station and took him into custody.

In court, he flashed an evil grin before he was ordered held without bail on murder charges.

Burke had been arrested by the NYPD four times since February, including for a meltdown at the Seventh Avenue and West 23rd Street station Feb. 14, when cops responded to a report of a man with a shovel who allegedly smashed several doors and threw a trash can onto the tracks.

His criminal antics involved a bizarre spiral from the lights of Broadway, where he once performed and appeared to have a bright future in the arts, a friend told The Post.

A rep for King Kong on Broadway did not respond to a Post request for comment.