Castro was a French empresario. He was born in Landes, France in 1786. While working for the banking firm Lafitte and Company, he became interested in the fledgling Texas Republic and worked to secure loans for the new nation. He came to Texas in 1841 to secure lands for a French colony and received a contract to settle families on the Medina River. Between 1844 and 1847 he brought over nearly 1000 people to settle in Castroville and neighboring villages. On a trip back to France in 1865, he became ill and died in Monterrey, Nuevo Leon. Castro County was named in his honor.