[1][2] He served in World War II and appeared in a U.S. Army revue called "Stars and Gripes".

After the war, a Columbia Pictures producer saw him performing on stage and offered him a screen test.

[1] He also appeared in Jailhouse Rock as Elvis Presley's character's prison mentor, and in Designing Woman (1957) as a punch-drunk ex-boxer who could only sleep with his eyes open.

Writing in The New York Times, film critic Bosley Crowther said that Shaughnessy's role in The Sheepman (1958) was the "item to be most grateful for", and called him ''a slag heap of pot-belly, wounded dignity and scowls.

[1] According to the Los Angeles Times, Shaughnessy once said that he always kept in mind "the old Irishman--the guy who refuses the dentist's novocain.