Glee star MARK SALLING‘s ego has gotten so huge, he’s become an outcast among the show’s group of tight-knit performers, say sources.

Fellow actors say that the 28-year-old hunk is only interested in his own solo music career and spreads lies about others – and the cast secretly despises him.

"Mark’s attitude of being better than everyone else is really turning people off," revealed an insider.

The actor – who plays Noah "Puck" Puckerman on the Golden Globe-winning show – was the first cast member following the popularity of Glee to release a solo album titled Pipe Dreams in October.

Ever since the LP hit shelves, Mark’s ego spiraled out of control.

Now, his former friends want nothing to do with him – and he’s feeling the rejection, says a source.

At a Jan. 22 party celebrating co-star star Naya Rivera‘s 24th birthday at the Bellagio in Las Vegas, Mark was left by himself in LA, said the source.

"The Glee cast is a very tight-knit family, and Mark has been acting like he is better than everyone else, keeping to himself and not bothering much with the group.

 "Mark is really only out for himself."