I remember the first time I watched Creepshow (waaaay back in '83) and during the Something to Tide You Over" segment I remember thinking, "Hey, it's that Shirley guy from Airplane!" It would be his last serious, dramatic role.
But the funniest memory I have of Nielsen is seeing him on a late night talk show (David Letterman, Carson, one of the two) and the host made mention of Nielsen's tendency to pull practical jokes on his movie sets. Nielsen then produced some little gizmo that made fart noises, said he'd had it for years, and had embarrassed more than a couple people with it. For the duration of the show (I haven't watched a late show in forever, but at the time guests tended to stay for the whole show rather than just do their segment and leave) each new guest was given the fart noise treatment. I remember there was some author pimping his book and at the most serious parts of his interview you'd hear "fffffffrrrrrrrrrrrrrt."
That's all it took. I became a lifelong fan on the spot.
He'll be missed.