Caroline Webster "Lina" Schermerhorn Astor was an American socialite of the late 19th century who was a leader of the social elite group known as the Four Hundred. She was married to William Backhouse Astor Jr., a businessman, racehorse breeder/owner, and yachtsman. Astor was a member of the prominent Astor family and became known as "the Mrs. Astor" or simply "Mrs. Astor".