James Hewetson (c. 1797–1870) was a Texas empresario.
Hewetson was born in Thomastown, County Kilkenny, Ireland in 1797, the son of Patrick and Honora (née Hoyne). After studying medicine, Hewitson emigrated to the United States.
Already set on moving from the United States to Mexico, Hewetson encountered Stephen F. Austin in St. Louis, Missouri. Hewetson followed Austin to New Orleans and then was among those who accompanied Austin's first visit to Texas in 1821. Hewetson parted ways with Austin at San Antonio de Béxar and continued further on into Mexico, eventually settling at Saltillo and Monclova in Coahuila. Hewetson was involved in various mining, manufacturing, and mercantile businesses, as well as with local government in Coahuila.
Hewetson and James Power partnered as empresarios in 1826 to establish a colony in Texas. After forming the partnership, Power and Hewetson applied to be empresarios with the Mexican government in 1825 in order to begin a colony on the Texas coast with Mexican and Irish families. The original 1826 application requested a grant between the Nueces and Sabine Rivers, but in 1828, the Mexican government instead offered the strip of land between the Guadalupe and Lavaca Rivers. The next year, Power and Hewetson requested more land and their holdings were extended west to the Nueces River, which included Nuestra Señora del Refugio Mission. Ownership disputes with other empresarios forced Power and Hewetson to cede some land east of the Guadalupe River and the new eastern boundary was drawn at Coleto Creek.