The eighteenth season of The Simpsons aired on Fox from September 10, 2006, to May 20, 2007, with Al Jean continuing as showrunner. This season was notable for its milestone finale, "You Kent Always Say What You Want," which marked the series' 400th episode. During this time, the franchise also celebrated its 20th anniversary, tracing its origins back to April 19, 1987, when the characters debuted as shorts on The Tracey Ullman Show. The season featured an impressive array of guest stars, including Kiefer Sutherland, Metallica, The White Stripes, Natalie Portman, and Stephen Hawking, alongside recurring favorites like Betty White and Eric Idle. Additionally, it included seven hold-over episodes from the previous season's production line, making it a mix of fresh stories and carryovers from the show's evolving creative process.