Sir Leonard "Len" Blavatnik (born June 14, 1957) is a Ukrainian-born British businessman, investor, and philanthropist. He made his fortune through business via diversified investments in myriad companies through his conglomerate company, Access Industries. In 2015, he was named Britain's richest man with an estimated net worth of £17.1 billion as of April 2015. In 2017, Blavatnik received a knighthood for services to philanthropy.

In the Sunday Times Rich List 2015, Blavatnik was listed as the UK's richest person, with a fortune of £16.9 billion. Forbes ranks Blavatnik as the 16th richest in the world as of April 2015.