The world mourned the late David Bowie Monday, including late night talk show hosts.  Both Jimmy Fallon and Conan O'Brien remembered the fallen rock star in touching tributes that can be viewed in the first 2 YouTube clips below.  The third clip is a tribute from alt-rockers El Vy, who served as the musical guest on "Late Night with Stephen Colbert".  Bowie passed away Sunday at the age of 69 after an 18-month battle with cancer, which he kept very private.  The icon even recorded his latest album, Blackstar, while undergoing chemotherapy and radiation treatments.  The album was released just two days before his death.