Karen Alexandria Kain, CC (born March 28, 1951 in Hamilton, Ontario) is a retired Canadian ballet dancer.
She worked as a guest artist with Roland Petit's Le Ballet National de Marseilles, the Bolshoi Ballet, the London Festival Ballet, the Paris Opera Ballet, the Hamburg Ballet, the Vienna State Opera Ballet, and the Eliot Feld Ballet.
In the late 1970s Kain stopped dancing, but resumed again in 1980 with the National Ballet of Canada, where she danced for a further 15 years. Kain retired as a professional dancer in 1997.
In 1996, Kain reunited with Frank Augustyn to appear in her husband Ross Petty's panto production of Robin Hood at Toronto's Elgin Theatre.
In 1976, she became an Officer of the Order of Canada and was made a Companion of the Order of Canada in 1991. She holds honorary degrees from the University of Toronto, York University, McMaster University, Trent University, and the University of British Columbia. In May 1998, the French Government named her an Officer of the Order of Arts and Letters. Among Kain's other honours are the Performing Arts Award (1992) and the National Arts Centre Award (1997). In 1996, she became the first Canadian to receive the Cartier Lifetime Achievement Award. The choreographer Marguerite Derricks cited Kain as one of her heroes.

Kain is the president of the Dancer Transition Resource Centre. In 2004 she was appointed chair of the Canada Council for the Arts, a post she resigned in early 2008 to concentrate on her role as artistic director of the National Ballet. In 2007 Karen Received the Barbara Hamilton Memorial Award from the City of Toronto.
Her autobiography, Movement Never Lies, was published in 1996 by McClelland and Stewart.
Kain's brother, Kevin Kain, is a noted tropical medicine expert based in Toronto, Ontario; she has three younger siblings.