Tekken 6: Bloodline Rebellion:

Anna suffered an embarrassing defeat at the hands of her sister, Nina, during The King of Iron Fist Tournament 5. Anna searched for an opportunity to exact her revenge on Nina after the fight; however, Nina had been hired for a covert operation by an unknown employer and has been virtually invisible since.

War engulfed the world in the wake of the chaos triggered by the Mishima Zaibatsu. Anna caught wind of top-secret information that linked Nina to the Mishima Zaibatsu. Anna joined the elite G Corporation with the hope that it might lead her to her sister and a chance to exact revenge.

Tekken 5:

Sister and rival of Nina Williams, Anna had been leading a dull and boring life since the disappearance of her sister. That all changed one day when she received a phone call from Nina.

Several days later, the two met again after having been apart for two years. However, upon seeing her sister's face, Nina immediately opened fire. Anna returned fire and the ensuing gun battle lasted for days.

Both sides failed to land a decisive blow and it was decided they would settle things at The King of Iron Fist Tournament 5.

Anna vowed to eliminate her sister once and for all.

Tekken 3:

Nineteen years ago, Kazuya Mishima confided some alarming news to Anna. Her sister, Nina Williams, was planning to become a guinea pig of Doctor Boskonovitch's "Cold Sleep". As much as they quarreled, Anna would miss her sleeping sister. Even worse was the fact that she would continue to age while her sister was frozen in time. Anna also went to Dr. Boskonovitch, subjected her to the Cold Sleep, and asked to be awakened at the same time that Nina was awakened.

Sensing the God of Fight's evil presence, both Nina and Anna awoke nineteen years later. Anna awoke without any side effects, but Nina had somehow lost all of her memories of Anna, which saddened Anna, because she was making an effort to continue their sibling rivalry. Now, rather than fighting Nina, Anna felt the need to help Nina and prevent her from again becoming an assassin.

Tekken 2:

Tekken 1:

Anna is the younger sister of Nina Williams. Anna learned her Aikido techniques from her mother, a female national Aikido champion. Her father, Richard Williams, taught Nina assassination techniques, but he has neglected Anna for years and never taught her assassination techniques.