Alexei Osipovich Ratmansky is a Russian-American choreographer and former ballet dancer. As of April 2014 he is the artist in residence at the American Ballet Theatre. From 2004 to 2008 he was the director of the Bolshoi Ballet. (via Wikipedia)
IMDB have two people - Aleksei Ratmansky nm3428296 and Alexei Ratmansky nm6224891. These are both the same person.