He was a hunter who saved John Winchester's life many times. He stopped hunting after an incident in Albuquerque, which Sam and Dean know about. The details of what happened are not revealed, but they were bad enough that he left hunting and voluntarily checked himself into a psychiatric hospital. After patients started dying at the hospital, Martin called in Sam and Dean as he was still too traumatized to do anything himself. He was eventually able to identify the monster as a Wraith and explain its abilities and weaknesses to Sam and Dean, but refused to help fight despite being given a silver-plated letter opener when the Winchesters went after the doctor they believed was the Wraith. Despite this, Martin intervened in time to save the doctor by showing Sam he wasn't the Wraith since his skin wasn't burning when touched by silver. When the Wraith drove Sam crazy, Martin helped Dean figure out that it was causing their crazy symptoms and went with him to check out a suspect, finding the real Wraith, J. Forman there. Martin injured the Wraith with his letter opener, but Karla called for the orderlies. As Dean went after Karla, Martin stayed behind to take care of the victim and hold off the orderlies, allowing Dean to save Sam and kill the Wraith.
When Sam is hallucinating, his hallucination of Dean mentions how quickly Martin lost his sanity and said he was shooting at nothing.
It has been revealed by Sam that he kept in touch with Martin. Once Martin was discharged from the mental institution, Sam asked Martin to track and report Benny's movements. Martin did as requested and found Benny to be clean. However, during the events when Benny was being invited by an old vampire friend to help in creating a new nest, Martin grew suspicious of Benny and was convinced it was Benny who was responsible for the death of a local. He then alerted Sam about it.
As it turned out, Benny was aware of Martin watching him but didn't worry himself about it though was avoiding the nest and was trying to stop the other vampire from killing more people. However, Martin and Sam remain convinced Benny was being untruthful. This placed them at odds with Dean, who was not only keen on proving Benny was innocent, but also believed Martin was not mentally sound to resume his occupation as a hunter. While Dean helped Benny kill the rogue vampire, Martin and Sam tried to hunt Benny. Sam was diverted from their hunt by a message from Amelia's number, which later proved to be Dean trying to rid Sam off the case.
Although the case appeared to be solved, Martin was adamant in wanting to kill Benny. Despite Dean's suggestion for Martin to stop hunting, the latter took Benny's great granddaughter Elizabeth hostage to lure the vampire back from hiding. His plan worked, and Benny returned to try to save Elizabeth. The old hunter eventually met his death at the hand of the enraged vampire.
- Season 5
- Season 7
- Hello Cruel World (mentioned only)
- Season 8
- Martin's death mirrors Travis' who was also killed because he angered a monster by holding someone that the monster cared about. (Elizabeth to Benny, Michelle to Jack)