Mars is first male in five years to take top artist honors, while Timberlake's '20/20' leads Billboard 200 and 'Thrift Shop' sits atop Hot 100.
Bruno Mars rules as Billboard's top artist of the year for 2013.
The singer/songwriter triumphs thanks to the incredibly consistent performance of his most recent album, "Unorthodox Jukebox," and its singles. Mars is the first man to rule as artist of the year since 2008, when Chris Brown topped the year-end Top Artists tally. Since then, it's been an exclusive club of solo women, with Taylor Swift taking the honor in 2009, Lady Gaga in 2010, and Adele in 2011 and 2012.