Mickey Spillane guest starred as a victim in the 1974 Columbo episode "Publish or Perish". Like most victims on the show, he's not around for long, not like his starring role in The Girl Hunters more than a decade earlier. He didn't quit his day job as a pulp writer, which is probably for the best. He more or less comes off well playing a pulp writer on Columbo. Not writing detective stuff, as Spillane did in real life, but Vietnam war stuff.
The villains are two--a publisher (Jack Cassidy) and the explosives nut (John Chandler) he hires to kill Spillane. Chandler gives an effective, over the top performance, almost on the level of Frank Gorshin--he seems like a real maniac. He does the job for Cassidy in the hopes Cassidy will publish the book he's written on homemade bombs.
Cassidy is more of a deliciously cheesy '70s TV villain. Columbo's tactic for outsmarting him is clever and pretty satisfying for anyone who likes to analyse writing.