While she did in fact birth three of the most influential characters in the series, Mary was never able to take on the maternal role herself. For the sake of technicality, Mary will be receiving honourary mention instead of a place in the ranks. This is probably for the best, because she's absolutely impossible to place. She makes plenty of mistakes, grave ones, but she also makes some of the most drastic moves for redemption. Making Ali think she was losing her mind was not her finest moment, but once she realises that Archer is a greedy mastermind, she bails on their plans and works to make amends. She later takes the blame for a murder she didn't commit and accepts a life sentence to exonerate her daughter and niece, which I can respect.