Jun may be from a fighting series rather than an RPG, but that doesn't make her any less of a great mother, so she manages to sneak in at the end of this list as bonus entry -- yes I know I've cheated a bit, but she is a bonus mom.
At face value, Jun plays an extremely minimal role throughout the series, as she only appears in one canon game -- Tekken 2. However, this role portrays who she was as a person and what she meant to her son, Jin.
The Mishima/Kazama saga throughout the fighting franchise has been one of hatred, evil plotting, bloodshed and devil related mishaps. Both Jin and Kazuya have been plagued by the devil gene for the entire duration of the series, but sadly Jun, the only ounce of purity and goodness in the family, died, or at the very least, disappeared.
Jun was determined to guide Jin and Kazuya through their struggle with the demonic gene. So much so that her very presence kept it at bay. As a character she is wildly juxtaposed to her family as a nature loving, calming influence.
A lesson to be learned here is that amidst the chaos of our lives, a mother can sometimes be the only source of happiness in our lives. Don't take that for granted.