We're preceptors, beholders, chroniclers of all that man does not understand. We share our findings with a few trusted hunters – the very elite. They do the rest.
The Men of Letters is a secret organization of scholars who research the supernatural. They undergo a period of teaching in areas of arcane knowledge and rituals and, if they pass, are initiated into the most secret knowledge. They saw hunters as a necessary evil in doing their work, but viewed their use of violence with contempt.
- The symbol of the group is the Aquarian Star.
- Membership of the group is open to both men and women.
- Membership is hereditary.
- Albert Magnus is the name members use when going incognito. Albertus Magnus was a German Dominican friar from the 13th century who advocated the peaceful coexistence of religion and science.
- They have stored in the Bunker their collected knowledge "every object, scroll, spell ever collected for thousands of years under one roof... the safest place on earth, warded against any evil ever created." The key to this place was placed in a box, and given to Henry Winchester to protect from the demon Abaddon.
The order was seemingly destroyed by a Knight of Hell, Abaddon, on August 12, 1958. The surviving members Henry Winchester, and an elderly Larry Ganem, both died at the hands of Abaddon in 2013.
The only known survivor of the Men after the deaths of Henry and Larry was Cuthbert Sinclair, a member of the group who was expelled in 1956 due to his experimenting with spells. he was killed in 2014 by Dean.
In 1958 Abaddon, one of the Knights of Hell, was sent by party or parties unknown to kill the members of the group who were gathered in Normal, Illinois. They were gathered for the initiation of Henry Winchester and Josie Sands.
After possessing Josie, Abaddon killed David Ackers and Ted Bowen, and blinded Larry Ganem. She then went on to burn down their quarters before following Henry through the portal created by his blood spell, which took him to 2013. Henry has with him the Key to the Bunker - which contains where all the knowledge the Men of Letters have collected. It is later learned that the organization has been disbanded after the Abaddon incident. The only known survivors of that incident were Henry and Larry, but both of them were killed by Abaddon in her search for the Box in 2013.
Sam and Dean travel to the Men of Letters Bunker in Lebanon, Kansas and find it abandoned, having apparently been deserted in response to Abaddon's attack. Searching for any groups of hunters that worked for the Men that might still be active, Sam and Dean find a case dealing with the Judah Initiative, a group of Rabbis that worked with the Men during World War II.
Looking for information on how to break Zeus' curse which is affecting Prometheus' son Oliver, Sam and Dean search through the Men's books in the Bunker and find the journal of Greek hunter Dracopolis which the Men had translated into English. From the journal they learn how to summon, trap and kill Zeus.
Sam and Dean discover that the Men of Letters recorded every demonic possession for 300 years up until their destruction in their files. They possessed a rating system for the type of possession with a possession like the one in The Exorcist being a Class 2 Infernal Event. Sam and Dean discover a file for a Class 5 event labeled "weird!!!" and find a film taken by initiate Josie Sands of a different type of exorcism that fails. They learn from Father Simon, one of the priests that took part in the exorcism, that the Men of Letters were interested as the other priest, Father Max Thompson, had a theory that a demon could be cured and turned back into a human being. The exorcism was a failed attempt at doing that. Thanks to the discovery of this file, Sam and Dean eventually learn of a way to cure a demon and complete the third trial.
After Sam and Dean put Abaddon back together, she reveals that she was the one that killed Father Thompson and learned about the Men of Letters and Josie Sands from him which is what led to her attack that destroyed the Men of Letters.
In 1935, two Men of Letters, James Haggerty and Peter Jenkins travel to the recently finished Bunker to work on cases that come up, but get bored quickly. Sometime later, Dorothy contacts them to help her kill the apparently-invincible the Wicked Witch of the West, but the Wicked Witch breaks free and possesses Jenkins, forcing Haggerty to kill him. Dorothy binds herself and the Wicked Witch to stop her and Haggerty spends the rest of his career trying to find a way to save Dorothy and stop the Wicked Witch. He eventually comes upon the idea of using poppy seed extract from the Oz books and makes a deal with a fairy to get some. In the present day, Dean accidentally releases Dorothy and the Witch and working together with Charlie Bradbury, they stop her once and for all, solving the Men's old case.
After discovering that Sam still possesses some of Gadreel's grace, Castiel looks through the Men's archive for further information. Castiel discovers from one of their books that is written in Enochian that part of an angel's grace stays inside their vessel when they leave it and that it is harmless to the vessel. However, he also finds a confidential file written by Man of Letters James Haggerty that states that the Men believed that if the grace was extracted, it could be used in a tracking spell to find the angel but they were never able to test it as they couldn't find anyone to use it on. Sam and Castiel try the spell, extracting the grace with one of the Men's implements, but Castiel is forced to stop when the procedure nearly proves fatal to Sam. Though they get some of Gadreel's grace, it proves to be not enough for the Men's spell to work.
While looking for the First Blade, Sam and Dean learn it was acquired by a man going by the name Magnus, the alias used by the Men when they want to remain incognito. Looking through the Men's files, Sam and Dean figure out that Magnus was Cuthbert Sinclair, the Men of Letters master of spells who warded the Bunker and was kicked out of the society after he wanted to make the Bunker completely invisible and only accessible by spell. After tracking down Magnus, Dean is forced to kill him with the First Blade to save himself and Sam.
Investigating a possible demonic possession in Milton, Illinois, Sam learns that in 1958, shortly before their initiation, the Men of Letters sent Henry Winchester and Josie Sands on a field mission to investigate a similar occurrence to help them gain experience. During the mission, Henry expresses doubt about joining the Men as he worries about leaving his family. Eventually, Henry and Josie find the four demons responsible and exorcise two. One of the others, the Knight of Hell Abaddon proves immune and plans to possess Henry to investigate and infiltrate the Men of Letters. Josie convinces Abaddon to possess her instead and she does, telling the remaining demon, Sister Agnes to pretend to be exorcised so she can trick Henry and to continue their work once she is gone. The ploy works and Henry leaves with Abaddon, unaware of the truth of what was going on, that the demons were really stealing people's souls. The experience also causes Henry to lose all doubt about joining the order.
In the present, at The Bunker, Dean goes through the Men's files while on his obsessive hunt for Abaddon and Sam joins him after learning that Abaddon is stealing people's souls in order to create her own demon army loyal only to her, meaning they need to stop her as soon as possible.