James Strickland's son
From Futurepedia, the Back to the Future Wiki
The son of James Strickland rode alongside his father on September 5, 1885, the night of the Hill Valley Festival, when Buford Tannen and his gang wanted entry into town. After James dealt with Tannen, he taught his son the fundamental principle of "discipline", a concept he would carry with him and teach his children and so forth, eventually resulting in the strict discipline exemplified by Mr. Strickland.
[edit] Behind the scenes
In the novelization, he witnesses his father being shot in the back by Tannen and is given the same advice for the final time.
