score:5
I cant for sure say the first person to be made a citizen, but I do know that Benjamin Milam was made a citizen in 1824.
James Powers was made a citizen sometime before 1828 (probably with Hewetson in 1827)
James Hewetson in 1827:
Others off the top of my head are DeWitt, Sterling Robertson,Robert Leftwich, Stephen Austin, and anyone that was part of the original Texas land grants.
Upvote:6
Piecing together some thin threads, I can argue that someone was naturalized prior to that date.
All colonists were expected to become naturalized Mexican citizens, and they were also supposed to follow the state religion. Wikipedia:Mexican_Texans
Further down in the same article: (emphasis added)
Approximately 3420 land grant applications were submitted by immigrants and naturalized citizens, many of them Anglo-Americans. The first group of colonists, known as the Old Three Hundred, arrived in 1822 to settle an empresarial grant that had been given to Stephen F. Austin by the Spanish. [Ibid]
This argues that there were naturalized citizens in 1822
A third quote reinforces that impression:
In 1829, Mier y Teran issued his report, which concluded that most Anglo Americans refused to be naturalized and tried to isolate themselves from Mexicans. [Ibid]
"most Anglo-Americans refused to be naturalized..." implies that some complied with the provisions.
I can't give you the name of the individuals, but these quotes from 1822 and 1829 suggest to me that the individual in 1833 was not the first.