The decades-long history of "Saturday Night Live" is celebrated with an epic special featuring past hosts, cast members and music guests.

Host Chris Pratt; Ariana Grande performs.

Host Sarah Silverman; Maroon 5 performs.

Host Bill Hader; Hozier performs.

Host Jim Carrey; Iggy Azalea performs.

Host Chris Rock; Prince performs.

Host Woody Harrelson; Kendrick Lamar performs.

Host Cameron Diaz; Bruno Mars & Mark Ronson performs.

Host James Franco; Nicki Minaj performs.

Host Martin Freeman; Charli XCX performs.

Host Amy Adams; One Direction performs.

Host Kevin Hart; Sia performs.

Blake Shelton hosts and performs tonight.

Host J.K. Simmons; D'Angelo performs.

Host Dakota Johnson; Alabama Shakes performs.

Host Chris Hemsworth; Zac Brown Band performs.

Host Dwayne Johnson; George Ezra performs.

Host Michael Keaton; Carly Rae Jepsen performs.

Host Taraji P. Henson; Mumford & Sons performs.

Host Scarlett Johansson; Wiz Khalifa performs.

Host Reese Witherspoon; Florence & The Machine performs.

Host Louis C.K.; Rihanna performs.