Martin McFly was the name of Seamus McFly's brother.
Irish by birth, Martin arrived in America with his brother and his brother's wife Maggie during the early 1880s. However, Martin had a problem in that he was always trying to prove that he wasn't a chicken. During one such encounter in Virginia City, Nevada, Martin was fatally stabbed with a bowie knife during a barfight.
- Back to the Future Part III (Mentioned only)