Blue is an anthropomorphic characters introduced in M&M's commercials since 1996. He was originally voiced by Phil Hartman but was replaced by Robb Pruitt in 1998. He is the second nut being, which is Almond. The first being is Yellow, which is Peanut.
Gallery
Videos
M&M's - Breath (1996, USA)
M&M's - Pool (1996, USA)
M&M's - And You Were There (2004, USA)-0
M&M's - Cupboard (2010, USA)
M&M's - Power Walk A Parody of Monsters Inc. Bloopers (2010, USA)