Monday was a big night for Jimmy Fallon, as he took the reins as host of his first Tonight Show. Jimmy had plenty of support for his debut, with Kim Kardashian, Lindsay Lohan, Tina Fey, and Sarah Jessica Parker all joining in on the fun for his $100 bet skit. The star power kept coming with his first guest, Will Smith, who helped him dance through the "Evolution of Hip-Hop Dancing," and U2, who performed at Top of the Rock. Jimmy's still bringing star power; Tuesday night he had Jerry Seinfeld and Kristen Wiig — who dressed up like Harry Styles — join him in front of the cameras, and Wednesday was all about Bradley Cooper, Emma Thompson, and Tim McGraw. Thursday brought Will Ferrell and First Lady Michelle Obama, who were game for an appearance on Jimmy's series "Ew!". Scroll down to see all the stars so far and get excited for Justin Timberlake's appearance tonight!