Complex sentence: Franklin Edward "Frank" Kameny (May 21,1925--October 11,2011) was "one of the most significant figures" in the American gay rights movement.
Split into simpler sentences: Franklin Edward "Frank" Kameny (May 21,1925--October 11,2011) was an American gay rights activist. He has been referred to as "one of the most significant figures" in the American gay rights movement.