Thomas Castellanos (born August 26, 2003) is an American football quarterback for the Florida State Seminoles.

[2][4] Castellanos attended Ware County High School where he played football, basketball and track and field.

[8] He committed to play college football for the UCF Knights, choosing them over Florida State and Georgia.

[9][10] As a true freshman with the UCF Knights in 2022, Castellanos appeared in five games and completed 9-of-16 pass attempts for 75 yards.

[12][4] Entering the game with his team down 14–0, he helped them comeback before losing in overtime, leading them in passing and rushing while also being responsible for all three of their touchdowns.

[16] Castellanos ended the season as the second-most prolific rushing quarterback in the FBS, only behind LSU's Jayden Daniels.

[citation needed] On November 13, 2024, head coach Bill O'Brien announced FIU transfer Grayson James would get the start over Castellanos at SMU.