“Boardwalk Empire” actor Michael Stuhlbarg was spotted leaving his Upper West Side apartment Monday morning — his first public appearance after he was allegedly struck by a homeless man with a lengthy rap sheet in a random attack Sunday night.

The 55-year-old actor, who is set to take the stage Monday for the first preview of his upcoming Broadway production “Patriots,” was wearing all black and carrying several bags as he headed out.

Stuhlbarg was walking near East 90th and East Drive Sunday just before 8 p.m. when 27-year-old Xavier Israel allegedly struck him in the back of the neck with a rock, causing an abrasion.

Israel, who is homeless, has previously been arrested for two assaults as well as a robbery, all of which took place in January 2022, police and sources told The Post.

Stuhlbarg was attacked less than 2 miles from where his “Boardwalk Empire” character, Arnold Rothstein, was fatally shot in the popular HBO drama