- "Alex, I gave you 5 days. You failed. You should have died in Vorkuta."
- — The father to Alex.
Mr. Mason is the father of Alex Mason, Marion and Dot. He sent three letters to Alex's CIA account under the name Dad-Letter1.txt, Dad-Letter2.txt and Dad-Letter3.txt. He is also the paternal grandfather of David Mason, and also the great-grandfather of Jessica and Savannah Mason.
Mr. Mason fought in World War II at Makin Atoll with the United States Marine Raiders. He received a Purple Heart for his time there. After a few years of his son's departure to the military, his wife fell ill and her doctor was unable to cure her. Accepting the inevitable, he contacted his children to see their mother for the last time. He saw Marion arrive along with her sisters, but failed to find Alex. He sent eight more letters to Alex, asking for his excuse, and still did not receive a reply. He sent one last letter, stating that the funeral service would be in five days. After this last letter, Alex failed to make up during his grace period and had a falling out with his father.
In his final message to Alex, he calls him "Alex" and signs off with "your father", unlike his previous letters where he called him "son" and signed off with "dad". This shows Alex that he no longer considers him family.