Helen Hayes MacArthur (née Brown; October 10, 1900 – March 17, 1993) was an American actress whose career spanned eighty-two years. She eventually received the nickname "First Lady of American Theatre" and was the second person and first woman to have won an Emmy, a Grammy, an Oscar, and a Tony Award (an EGOT). She was also the first person to win the Triple Crown of Acting; to date, the only other people to have accomplished both are Rita Moreno and Viola Davis. Hayes also received the Presidential Medal of Freedom, America's highest civilian honor, from President Ronald Reagan in 1986. In 1988, she was awarded the National Medal of Arts.

The annual Helen Hayes Awards, which have recognized excellence in professional theatre in greater Washington, D.C., since 1984, are her namesake. In 1955, the former Fulton Theatre on 46th Street in New York City's Theatre District was renamed the Helen Hayes Theatre. When that venue was torn down in 1982, the nearby Little Theatre was renamed in her honor. Helen Hayes is regarded as one of the greatest leading ladies of the 20th-century theatre.