An award-winning author, renowned poet, and civil rights activist, Dr. Maya Angelou – who passed away on May 28 at the age of 86 – was also a beloved mentor to TV host Oprah Winfrey. "She is one of the greatest influences in my entire life," Winfrey has said of her longtime friend, seen together in 2013. One of the best lessons Angelou taught Winfrey: "When you know better, you do better."