This is not a comprehensive list, just a list of the ones who affected my life in some way.

June
Anton Yelchin (actor) (6/19)
Prince Be (Attrell Cordes) of P.M. Dawn (6/17)
Michu Mezaros (actor, ALF) (6/13)
Kimbo Slice (mixed martial artist) (6/6)
Muhammad Ali (6/3)

May
Andre Fuentes (dancer, choreographer- most notably for Britney Spears, actor) (5/31)
John Berry (Beastie Boys) (5/19)

April
Billy Paul (singer) (4/25)
Prince Rogers Nelson (4/21)
Joanie Laurer (professional wrestler, actress) (4/20)

March
Nancy Reagan (First Lady 1981-1989, actress) (3/6)

February
Frank Kelly (actor, Father Jack Hackett of Father Ted) (2/28)
Maurice White (Earth Wind & Fire) (2/3)

January
Alan Rickman (actor) (1/14)

Wikipedia has a more comprehensive list covering anyone influential (both good and bad) here.