'Our Idiot Brother' Star Matthew Mindler Goes Missing at College

Matthew Mindler, the former child actor famous for starring opposite Paul Rudd in "Our Idiot Brother," has gone missing from his college in Pennsylvania ... according to police.

A freshman at Millersville University in Millersville, PA, Matthew has not been seen since Tuesday night and was reported missing late Wednesday after not returning to his dorm room and not returning calls from his family ... according to cops.

Police say Matthew was last seen walking away from his dorm at 8:11 PM Tuesday, wearing a white Millersville University hoodie with black stripes on the arm, a black backpack, jeans and white sneakers.

Cops say Matthew went to classes Monday and Tuesday but hasn't entered a classroom since.

We're told police are being flooded with tips and cops are following up on all leads.

Matthew's famous for his work as a child actor in 'Idiot Brother' and "Frequency" but he has not been acting for several years and just enrolled in college.