Kanye West
West's controversial incident the following year at the 2009 MTV Video Music Awards was arguably his biggest controversy, and led to widespread outrage throughout the music industry. During the ceremony, West crashed the stage and grabbed the microphone from winner Taylor Swift in order to proclaim that, instead, Beyoncé's video for "Single Ladies (Put a Ring on It)", nominated for the same award, was "one of the best videos of all time". He was subsequently withdrawn from the remainder of the show for his actions. West's tour with Lady Gaga was cancelled in response to the controversy, and it was suggested that the incident was partially responsible for 808s & Heartbreak's lack of nominations at the 52nd Grammy Awards.

Q: Kanye's tour with what artist was cancelled following his outburst at the VMA's?
Lady Gaga