Mischa Barton got caught up in a fight at Halloween party.

The former “O.C.” star was left furious when someone threw a drink over her at the Park Bar in New York City on Saturday after she accidentally stepped on his foot.

The Irish-American actress then threw her own drink at the unnamed partygoer’s face in retaliation.

An onlooker told Radar Online: "I was standing beside this guy at the bar when Mischa went past us carrying two drinks.

"The next thing I knew he threw his drink over her back and she turned around and asked him: ‘Did you just throw a drink over me?’

“The man responded that the drink was in retaliation for Mischa stepping on his shoe and she threw one of her drinks in his face.”

The incident took an ugly turn when the newly unemployed actress, who was dressed as a peacock, returned to her table and told her friends, who rushed to confront the man.

“Within a few minutes one of her male friends came over to confront the guy and asked him to step outside,” the source added. “Mischa’s friend left but then he kept coming back every few minutes to complain."

The two men then allegedly fought on the dance floor before two bouncers came and threw out the instigator - who had “a gash to his head and his knee was all cut up.”