Ralph Waite and Dick O'Neill: THE Dads of Tough Guys

Ralph Waite plays the grandfather of Booth, tough FBI agent, and the father of ultimate-tough-guy-never-to-be-contested Gibbs of NCIS.

Dick O'Neill was the father of "hotdog" Cagney (of Cagney & Lacey) and father-figure shop teacher to accident-prone Tim Taylor.

They don't really look a like . . . except they totally do. What is it about these guys that screams DADS? Or, rather, DADS TO THE TOUGHEST?

Okay, Dick O'Neill did play Dad to Cheers' non-tough Cliff Clavin.

Still . . .