J. K. Simmons voiced Stanford Pines in the series Gravity Falls .
He is known for voicing Cave Johnson in the video game Portal 2 ( 2011 ) , Tenzin in The Legend of Korra ( 2012 ) , Kai in Kung Fu Panda 3 ( 2016 ) and Mayor Lionheart in Zootopia ( 2016 ) .
J. K. Simmons