Bartimaeus (bar-ti-may-us) is a fictional character in the Bartimaeus Trilogy written by Jonathan Stroud. He is a sarcastic djinni of the fourth level and 5,010 years old at the beginning of the first book. His many masters have included Gilgamesh, Solomon, a Ptolemy princeling, Tycho Brahe, Faust, and, most recently, the British boy magician Nathaniel (known as John Mandrake to his peers), who is his master for the duration of the trilogy.