Now that the final season of "Lost" is upon us, fans understandably have some burning questions. Did detonating the hydrogen bomb reset the time stream? Why does the Man in Black hate Jacob? What's the deal with the four-toed statue?

But most importantly: Will the ABC show's final 16 episodes live up to those from previous seasons, or will "Lost" totally fall apart in its final stretch?

For one reason or another, history hasn't been kind to quality shows at their close. Many a classic has completely imploded in its final season, thereby failing to go out gracefully and, in some cases, tainting the good stuff that came before.

Asylum takes a look at five shows that utterly lost it in their last season.

"The X-Files"
While "The X-Files" had its ups and downs at the tail end of its nine-year run, the final season was when things really unraveled. David Duchovny bailed at the end of season eight, popping up only a handful of times during the final season. While Gillian Anderson was still around, boring new Agents Doggett and Reyes (the Mulder and Scully that never was) were mostly called on to do the heavy lifting. Snooze.

One of the biggest TV disasters of all time, the final season of "Roseanne" finds the Conner clan winning the lottery and going from dysfunctional loudmouths to basically a noisier "Beverly Hillbillies." The final episode revealed that the entire season had been part of a book Roseanne had written to cope with Dan's death -- a total cop-out.

"Twin Peaks"
Before "Lost" and "The Sopranos," David Lynch's bizarro murder-mystery soap defined the modern "water cooler" TV series. But once the Laura Palmer murder mystery wrapped up midway through season two, the show struggled to figure out where to go. By the time the seriously freaky Lynch-directed series finale rolled around, pretty much no one was watching. Perhaps this is why "Lost" didn't explain the island during its first season.

"Gilmore Girls"
For six hilarious, heartwarming seasons "Gilmore Girls" was that perfect show that guys could safely watch with their girlfriends. (You can't hate any show that casts Sebastian Bach of Skid Row in the local garage band.) But then creator Amy Sherman-Palladino bailed for a short-lived Fox sitcom that nobody watched, sending the show into a huge creative shame spiral for its final season.

"That 70s Show"
Like "The X-Files," "That 70s Show"'s final season suffered from crucial cast members jumping from a sinking ship. In this case, it was Topher Grace and Ashton Kutcher who bailed after season seven. Grace's absence, in particular, was a huge loss, as the show was ostensibly about his character, Eric. When Fez is your main character, you know something has gone horribly wrong.