Riordan is a Irish surname that is derived from the Gaelic name "Ó Riordáin," which means "descendent of Riordán." The name is thought to have originated in County Tipperary in Ireland. People with the name Riordan are often described as intelligent, creative, and hardworking individuals. The name is relatively rare, but those who bear it are known for their strong sense of family values and their loyalty to loved ones. Riordan is a name that carries a sense of tradition and history, connecting those who bear it to their Irish heritage.