I'm trying not to make this a blog just of people who passed away, but I have a very small connection with him, having seen him in a couple of performances at Steppenwolf Theatre in Chicago. Most of the obituaries focus on the TV show Frazier, and a few mention his performance as William Faulkner in Barton Fink (which I should watch again one day soon), but only the Chicago-based obits talk much about Steppenwolf Theatre, even though doing live theatre was his main calling, he felt. After Frazier made him rich enough to do whatever he wanted, he mostly retired from Hollywood and just acted with Steppenwolf. Here is one that covers a breadth of his career.
I saw Mahoney in Conor McPherson's The Seafarer in 2009 and in Harwood's The Dresser in 2005. The Dresser was particularly notable as it also had Mike Nussbaum (a real fixture of Chicago stage) and Tracy Letts (the actor/playwright). I was supposed to see Mahoney in Enda Walsh's Penelope, though Mahoney had to pull out for family reasons and he was replaced by Letts. Letts did a fine job, though of course I would really have loved to see Mahoney in the role.
In many ways, Mahoney is a prime example for those of us who come to something they love late. He didn't start acting until he was 37, but made quite a career of it. I have no intention of taking up acting, but, in a sense, I do aspire to be a more creative person and do more with my writing, i.e. have it produced or get it published, now that I have reached my middle age.