'Saved by the Bell' Reunion?!

Jimmy Fallon has made it his mission to reunite the Bayside Class of 1993 -- and now Zack Morris and Jessie Spano are in!

On Monday night, Mark-Paul Gosselaar showed up on "Late Night with Jimmy Fallon" in full Zack Morris garb -- blonde hair, mismatched '90s fashion, brick cell phone and high-tops! Jessie (Elizabeth Berkley) called on the cell saying she's up for it!

Mr. Belding (Dennis Haskins) first signed on, and Fallon started an online petition for a reunion. Lisa Turtle (Lark Voorhies) soon followed. In April, Jimmy tried his hand at a telethon... when Jimmy started slacking, "Extra's" very own Mario Lopez took control!

Tiffani Thiessen and Dustin Diamond are the last two to go!