In French, a male ballet dancer is referred to as a danseur and a female as a danseuse. In the English speaking world, boys or men who dance classical ballet are usually referred to as (male) ballet dancers. Often "ballerino" is used in English-based countries as slang. Actually "ballerino" has overtones of superiority, like a principal dancer or a dancing master, and it's a term used rarely in the U.S. If we call him something other than "the guy who hoists the prima ballerina around the stage," it's probably "danseur." That's French.