Tonight marks the culmination of an incredible year for 'Fringe' fans in season finale "Brave New World, Part 2," a sentiment made all the more satisfying by the recent news that 'Fringe' will return for a fifth and final season.  More than that, however, the finale also sees more of the full return of Leonard Nimoy's villainous William Bell, which leaves some fans wondering, how did they coax the actor out of retirement?

Nimoy's presence on 'Fringe' has proved somewhat regular in its endgame throughout the last four years, even after the actor's claims of retirement.  While featuring most heavily in 'Fringe's second season finale episodes, Nimoy also maintained a presence in season 3 not only by lending vocals to an animated vision of himself, but also in his consciousness taking over that of Olivia Dunham (Anna Torv) the actress mimicking Nimoy's mannerisms with surprising aplomb.  But after the shocking revelation that a fully-reformed Bell had pulled the strings of season 4 villain David Robert Jones ('Mad Men's Jared Harris), 'Fringe' fans found themselves shocked and delighted to have Nimoy involved once more.

Says Nimoy of his return:

"I have really tried very hard to function as a retired person for the last couple of years, and I have passed up a lot of opportunities...I enjoy my personal life a lot these days. Having said that, I have a great place in my heart for the 'Fringe' company, for the Bad Robot company, and I really do enjoy being here in this very imaginative world."

Tonight's 'Fringe' season finale "Brave New World, Part 2" will see Walter Bishop (John Noble) coming face to face with his devious old partner once more, as the fate of both universes (as well as poor Astrid!) hangs in the balance, and judging by the latest promos, anything could happen.

There's just hours to go, but in the meantime take a look at two new behind-the-scenes featurettes of Nimoy explaining his surprise and delight to find himself working with the 'Fringe' crew, and scroll down even further for a first-look clip at tonight's season finale!  Tell us what you're expecting, and then tell us in the comments what you thought after the finale!