Simen Agdestein (born 15 May 1967) is a Norwegian chess grandmaster, chess coach, author, and former professional footballer as a striker with the Norway national football team.
Agdestein won seven Norwegian chess championships, including the 2005 title.
He is also the former coach of Magnus Carlsen, and brother of Carlsen's manager, Espen Agdestein.
He has authored and co-authored several books on chess, including a biography of Carlsen.