@rudely_murray said:

Truly gutted to hear this news... he was wonderful as Martin Crane, and a memorable presence in many films over the years.

Variety obit

I was only a casual fan of the show. But, I'd watch it from time-to-time and always enjoyed it. I especially liked Mahoney in the role of the down-to-earth, everyday dad. He had such a great screen presence AND he held-his-own even though he was playing opposite some high-powered scene-crunchers (no easy feat—I’m willing to bet)!

RIP