His real name was Gerard (or Gerritt, depending upon the source) von Honthorst. Born in Utrecht (Holland) in 1592, he was the son of a painter of some ability.
He went to Rome sometime in the after 1610, and absorbed the work of Caravaggio, which became his main inspiration for the rest of his artistic life. (The two never met; Caravaggio died in 1610, and Honthorst was only definitively documented in Rome in 1516.)
He was a painter much in demand, and was hired by various German courts, France, Spain, Holland, and Portugal.
The nickname “delle Notti” means “of the nights”. No doubt he earned this moniker because many of his works were painted night-time affairs, employing a dramatic use of light and dark. He died where he was born in 1656.