Tim Allen
Tim Allen's only participated in two good things in his entire career -- the Toy Story franchise and Galaxy Quest -- so this is just going to have to be a matter of taste. His Shaggy Dog remake is probably my personal pick for his worst film (Wild Hogs is awful, too, of course, but at least motorcycles are something to look at; I can't say the same about Tim Allen's face covered in CGI fur). But it's not like I've seen The Santa Clause 3 or anything. Could very well be even worse.

Sigourney Weaver
The woman's Ellen Ripley (and Zuul), so in all honesty she gets a lifetime pass to do whatever mediocre crap she wants, but there is just something particularly heartbreaking about how terrible Alien: Resurrection is (yes, despite the mighty Joss Whedon's writing). Ripley's a clone, then she's half alien, then the alien's half Ripley, then the alien has a baby, then the alien decides Ripley's its mom, and kills its real mom, and then the day is saved and everything's a disgrace to the franchise. Not really Weaver's (or Whedon's, calm down) fault, but still, the absolute worst.

Ray Liotta
Ray Liotta's been in a lot of great and/or enjoyable movies -- Goodfellas, Narc, Youth in Revolt, Corrina, Corrina, Observe & Report, even Smokin' Aces -- but he's also been in so many horrific piles of cinematic crap it's difficult to pick the worst. But, out of Uwe Boll's In the Name of the King: A Dungeon Siege Tale, the direct-to-DVD Jessica Biel vehicle Powder Blue, Wild Hogs, Operation Dumbo Drop, and the LL Cool J vehicle Slow Burn, among many others, I'm going to have to go with Operation Dumbo Drop. Not only was it embarrassingly bad, but, unlike Wild Hogs, it didn't make any money either. Even Denis Leary can't believe he did that movie.

Kelsey Grammer
I've decided to focus exclusively on all these people's film work here, which unfortunately means Hank is not eligible for mockery. Luckily, Kelsey Grammer also played General Patton in An American Carol, a Christmas Carol romp about how anyone even a centimeter to the left of Michael Savage is ruining the country. Also, it's about "Arab terrorists" hiring Michael Moore to help them with a propaganda film, which just makes sense. Down Periscope sucks, but at least it's not extremist drivel.

Jeanne Tripplehorn
Yes, she was in Waterworld. But I recently re-watched Waterworld, and it's actually kind of interesting, and not at all as bad as I remember it being? Sure, it had Kevin Costner's acting, at a time when his ego must have been at its most undeserved Everest height, and that shows, but it's still very ambitious in its premise and imagery, and really not entirely deserving of its brutally bad rep. So I'm giving it a pass for that reason, and for the reason that Jeanne Tripplehorn was also a rich a-hole in Guy Ritchie's remake of Swept Away, starring Madonna, which is far worse. Not that I've seen it recently, of course.