Robert Devereux, favourite of Queen Elizabeth I of England, is the best-known of the many holders of the title "Earl of Essex".
Born at Netherwood in 1566, Devereux was brought up largely on his father's estate in Wales, and was educated at Cambridge. In 1580, following the death of the first earl, his mother married Robert Dudley, Earl of Leicester, long-standing favourite of the queen. Essex did military service under his stepfather before himself making an impact at court and winning the queen's favour. In 1590, he married Frances Walsingham, daughter of Sir Francis Walsingham and widow of Sir Philip Sidney - who had died at the Battle of Zutphen, in which Essex had distinguished himself.
Essex's star was in the ascendant. In 1591, he was given command of a force sent to the assistance of the Protestant King Henry IV of France. In 1596, he distinguished himself once again, by the capture of Cadiz. In the meantime, he had effectively become the queen's foreign secretary and favourite, especially in the period after Leicester's death in 1588. However, he overreached himself when he attempted an expedition to the Azores, and failed again as Lord Lieutenant of Ireland, a post which Elizabeth had forced on him because she felt he was becoming too haughty.
Having permanently fallen out with the queen, Essex unwisely attempted a political coup, raising a rebellion and attempting to seize control of the city of London on February 8, 1601. He was arrested, convicted of treason, and executed at the Tower of London on February 25, 1601.
Devereux's title was inherited by his son, Robert Devereux, 3rd Earl of Essex.
The classic movie on this topic is the 1939 The Private Lives of Elizabeth and Essex starring Bette Davis and Errol Flynn.