Alexios IV Angelos or Alexius IV Angelus (Greek: Ἀλέξιος Ἄγγελος) (c. 1182 – February 1204) was Byzantine Emperor from August 1203 to January 1204. He was the son of Emperor Isaac II Angelos and his first wife, an unknown Palaiologina, who became a nun with the name Irene. His paternal uncle was his predecessor Emperor Alexios III Angelos.