Dame Mary Louise Webster,, known professionally as May Whitty and later, for her charity work, Dame May Whitty, was an English stage and film actress. She was one of the first two women entertainers to become a Dame. The British actors' union Equity was established in her home in 1930.

Equity, formerly officially titled the British Actors' Equity Association, is the trade union for the performing arts and entertainment industries in the United Kingdom.