Hugely influential in bringing Platonic ideas back into fashion, 15th century philosopher Marsilio Ficino also brought back the idea of "Platonic" love. He lived for many years with poet Giovanni Cavalcanti, to whom he wrote passionate love letters.
Father of the Harlem Renaissance Alain Locke influenced a wide range of writers, artists and musicians. He was also a closeted gay man, which isn't mentioned in most history books.
Francesco Algarotti, sometime lover of Lord Hervey and Frederick the Great, was a key figure in spreading art, music and architecture criticism throughout 18th century Europe.