Antonio "Tony" Ruiz was a human male alive in the mid 22nd century. A native of Cuba, Ruiz came to Sauria as a mining engineer and stayed on as a medic after plague struck the area of the planet he was working in.
In 2164 Ruiz met Charles Tucker III, who had traveled to Sauria on a Section 31 mission using the identity of Albert "Al" Sims. Because the two were originally from fairly close geographic areas and were both affected by the Xindi attack of 2153 the two became friends.
When Maltuvis began moving to take control of the entire planet, Tucker was ordered to return to Federation space by Harris. Ruiz also was ordered to leave, however he decided to remain and fight Maltuvis. When Tucker tried to remind Ruiz that he was one man, Ruiz quoted Fidel Castro in saying, "It does not matter how small you are if you have faith and plan of action!" The argument ended with Ruiz angrily punching Tucker, who promptly left, feeling himself no longer worthy to call himself Ruiz's friend. (ENT - Rise of the Federation novel: Tower of Babel)