Theobald I (French: Thibaut or Thibauld de Bar) (born c. 1158 – died 13 February 1214) was the count of Bar from 1190 until his death, and a count of Luxemburg from 1197 until his death. He was the son of Reginald II of Bar and his wife Agnès de Champagne. He became count when his brother, Henry, was killed in the siege of Acre. During the Albigensian Crusade, Theobald led an army to reinforce Simon de Montfort at the siege of Toulouse in June 1211.