1. (noun)Klein, Felix Klein German mathematician who created the Klein bottle (1849-1925)
2. (noun)Klein, Melanie Klein United States psychoanalyst (born in Austria) who was the first to specialize in the psychoanalysis of small children (1882-1960)
3. (noun)Klein, Calvin Klein, Calvin Richard Klein United States fashion designer noted for understated fashions (born in 1942)