Bisinus, Basinus, Besinus, or Bisin (Lombardic: Pisen) was the king of the Thuringii (fl. c. 460 – 506/510).
According to Gregory of Tours, Bisinus gave refuge to Childeric I, the Frankish king who was exiled by his people. After eight years under Bisinus' protection, Childeric returned to Tournai. Bisinus's wife Basina left him and joined Childeric.
The historical Bisinus bears some resemblance to the Bisinus described by Gregory of Tours, but the details are different: The Bisinus described by Gregory was the leader of a Thuringian confederation on the Rhine and his wife was a Lombard named Menia. He and Menia left three sons, Baderic, Herminafred and Berthachar, who inherited the throne from him. Daughter Radegund married the Lombard king Wacho.