Executive producer and director Barry Sonnenfeld made the announcement during Netflix's FYSee event in Los Angeles on Friday. Harris, Alfre Woodard and K. Todd Freeman were also in attendance.
Fillion will play Jacques Snicket, Lemony's (Patrick Warburton) brother, and Hale will portray Jerome Squalor, who is married to Esmé Squalor, portrayed by Punch. Sonnenfeld revealed during the panel that Esmé might be a potential love interest for Count Olaf (Harris). "We don't know for sure," he said in the clip below.
Rue will also have a season-long arc and play the role of a librarian who goes "on to better things." Meanwhile, Bart will be Vice Principal Nero who "almost makes Olaf seem like a nice guy."
A Series of Unfortunate Events debuted on Netflix on Jan. 13 and was quickly picked up for a second season. In honor of the show's renewal, Harris got his first tattoo -- the mystical eye that is the symbol of his evil and greedy character.
To see how Harris prepared for the iconic role, watch the video below.