Untitled Lemony Snicket's A Series of Unfortunate Events sequel (lost screenplay of unproduced adventure film; 2004-2008)
In 2004, Paramount Pictures and DreamWorks released Lemony Snicket's A Series of Unfortunate Events, based on the first three installments in the children's book series of the same name. After the film was released, there were rumors about a sequel based on the fourth, fifth, and sixth books.
In May 2005, producer Laurie MacDonald said "Lemony Snicket is still something Paramount is interested in pursuing and we're going to be talking with them more."
In October 2008, Daniel Handler, the author of the book, said that "a sequel does seem to be in the works. Paramount has had quite a few corporate shakeups, which has led to many a delay. Of course, many, many plans in Hollywood come to naught, but I'm assured that another film will be made. Someday. Perhaps." 
In June 2009, Brad Siberling, the film's director, confirmed he still talked about the project with Handler and suggested the sequel be a stop motion film, with each film being in a new medium, due to the young lead actors having grown too old to continue their roles. "In an odd way, the best thing you could do is actually have Lemony Snicket say to the audience, 'Okay, we pawned the first film off as a mere dramatization with actors. Now, I'm afraid I'm going to have to show you the real thing.'"
Eventually, the series was rebooted as a TV show on the streaming service Netflix, confirming that the sequel was cancelled. However, Joe Tracz, one of the writers on the series, confirmed in an interview with the 667 Dark Avenue forum that Daniel Handler wrote a screenplay for a sequel, and that aspects of this screenplay were borrowed for use in the Netflix series.
"I’m told there were various sequel drafts (Various Film Drafts?) over the years**, and Daniel shared one of them with the writers at the start of Season Two. In addition to adapting “Austere Academy” and “Ersatz Elevator” (with a comically brief stop at Lucky Smells), it featured a subplot about VFD trying to get an important book to the Baudelaires. That was the genesis of our Season Two Incomplete History of Secret Organizations arc – only in the film sequel, the book was a coded copy of The Luckiest Kids in the World, which, like The Littlest Elf, provided frequent ironic counterpoint. Also of note is that the film picked up where the first one left off, with the Very Fast Delivery mailman turning a corner, pulling off her disguise, and meeting a pregnant agent…"
As of November 2023, Daniel Handler is the only writer known to be in possession of the screenplay, though the entire writing staff of the Netflix series was able to read it.