Aidan is an anglicised form of the Irish name Aodhán, which itself is derived from the Old Irish name Áedán meaning "little fire." Áedán is a diminutive of Áed, meaning "fire". Aed, or Aodh, is a god of the underworld in Irish mythology. Variations of the name were popular in early Ireland, as several Irish kings and saints bore a variation of the name. It has increased in popularity throughout the end of the 20th century and into the 21st.