Thierry of Alsace was count of Flanders from 1128 to 1168. He his sometimes known as Derry or Dirk.

After the murder of Charles the Good, Thierry was one the claimants for the county. Due to the support of King Louis VI of France, William Clito became count instead. Thierry succeeded after William's death in 1128.

Preceded by:
William Clito
Count of Flanders Succeeded by:
Philip of Alsace