|Basilio Aguirre Olmos de la Vargas|
|Location||Sidewinder Gulch and El Matadero|
|Voice Actor||Gerardo Rodriguez|
Basilio is a tradesman who is searching for some lost Aztec treasure that was owned by his great-great-grandfather (a "hero of a man" who slaughtered many Aztec "heathens") and requests Marston's help in doing so.
After Marston finds the other pieces of the map, much to his devastation, there was no treasure. He then returns to his family to tell them of his failure.
- Basilio can speak both Spanish and English fluently, and it is implied he can also speak Dutch, German, and Italian.
- He has apparently left his family behind in the city to search for the treasure, and frequently receives messages from them, including messages from his children wanting their dad to come home. He eventually returns to them after he discovers there was no treasure.
- Basilios middle name is Aguirre. This may be a reference to the 1972 film Aguirre, der Zorn Gottes ('Wrath of God') by Werner Herzog. In that film, a character named Aguirre is driven insane in search of El Dorado, the mythical city of gold.
- According to him, he has been searching for 10 years.
- Basilio's treasure map is a match for the Escalera Catacombs in the mission "A Civilized Man", suggesting that the treasure he is really searching for (although he doesn't know it) is the mask which caused the zombie apocalypse.
Complete a task for a Stranger.
Complete 15 tasks for Strangers.
Attain 100% List in the singleplayer game completion list.