"I think there was a bunch of people out there who were really hungry for things that were going to surprise them and make them think and make them write their own version of the story, and I think those are the type of people who gravitated toward 'Lost,'" Fox said.
"I think it's a very demanding show. You have to pay very close attention, and it's not something you can sort of just pop in and out of," he said. "It's not something you can just passively sit back and watch. You have to actively participate in it. You have to look for clues in it. And there is a certain segment of the TV audience that really enjoys that."
Fans are also expecting the return of characters previously killed off -- including Charlie, played by Dominic Monaghan, now of "FlashForward" fame, and Boone, played in the first season by Ian Somerhalder. Also returning is Emile de Ravin in the role of young mother Claire, who wandered into the woods in season four and left her baby to be raised by Kate, the freckled fugitive.
While the show has leaned heavily on sci-fi elements like time travel, portals and a shape-shifting black smoke monster, it largely remains a character study.
So when "Lost" lights up the small screen for its final season, fans will eagerly anticipate the resolution to the Jack-Kate-Sawyer love triangle. Sawyer had gotten all cozy with Juliet in season five, but since her face was about five inches from the nuclear blast in the season finale, Sawyer could very well be back in the running for Kate's affection.
"It feels like a show about all of us," Fox said, "and if you're willing to go on that ride and if willing suspension of disbelief is something you're into and you like to play with that, it's a good ride."
Losties will also want to know whether Sun and Jin -- currently both on the island, but stuck 30 years apart -- will ever meet again and whether Jin will meet the miracle daughter he conceived on the island.
Will Jack forgive himself that his father -- who, by the way, may or may not be dead -- fell off the wagon? Will Ben pay the ultimate price for his scheming ways? And will any more polar bears slip through the portal?
Some critics complained midway through the show's run that its creators and producers were losing focus, drawing viewers deeper into a web of questions that may have no answers.
But last season's concluding episodes seemed only to solidify the mind-bending plot lines of good versus evil, destiny and spirtuality that have stretched across all five seasons.
At the center of the show's debate of faith is John Locke, played by Terry O'Quinn. His storyline was intense from the very first season, when it was revealed the man, who was up and walking around the mysterious island, had boarded Oceanic flight 815 in a wheelchair, paralyzed from the waist down.
Even O'Quinn's character's name has been the subject of intense analysis -- John Locke was also a 17th century philosopher who influenced many of the Enlightenment's greatest thinkers.
O'Quinn told "Nightline" that the show's final season has been a mixed blessing for him.
And even though he is as famously tight-lipped as the rest of the cast and crew, O'Quinn said his expectations are just as high as the viewers'.