Walsh did not appear in films until 1983, when he had a minor role in Eddie Macon's Run. Over the next 15 years, he appeared in over 50 feature films, increasingly taking the bad guy role for which he is well known, such as Sergeant Major Dickerson in Good Morning, Vietnam. On television, he again portrayed an evil character, prison warden Brodeur on The X-Files in 1995 in the episode "The List".