Broderick Crawford as John 'Ripley

Ruth Roman as Kate Martell

Martha Hyer as Connie Anderson

Marisa Pavan as Julie Angelino

Max Showalter as Dave Millson

Kenneth Tobey as Zack Stewart

Gene Reynolds as Vince Angelino

William Johnstone as FBI Chief Frank Pace

Harlan Warde as Greg Barker

Jay Adler as Uncle Max - aka Charles Martell

Claude Akins as Matty Pavelich

Suzanne Alexander as Brenda Ralles

Myra Marsh as Mrs. Downes

Joe Bassett as Joe Walpo - aka Joe Allen

William Schallert as Ben

Alan Dexter as Lt. Jake Kuppol

Stafford Repp as Boxing Manager