Name: Nina Williams

Height: 161cm (5′ 3⅜″) 

Weight: 49kg (108 lbs) 

Eyes: Blue

Hair: Blonde

Blood Type: A  (changed during cryosleep) 

Nina and her younger sister Anna come from the island of Ireland and both have a intense rivalry in everything.

Her father Richard Williams is former IRA assassin who moves from Northern Ireland to the Republic of Ireland, to escape his past. He meets British Aikido champion Mrs. Williams and the couple marries. His marriage to British Aikido champion created a bloodline that would spawn a child with incredible talent and killer instinct. 

The sisters were taught in various forms of martial arts as assassination martial arts, aikido and koppojutsu since young age. Nina has an outstanding fight sense and acquires her unusual combination of skills from her parents. She learns assassination techniques from her father and Aikido for self-protection from her mother. She has a lethal fighting style which consists out throwing, grappling and clamp holding of opponents. She became instantly fan favorite due to her speed, lethal movements and chain throwing movements. Her strength is on par with other opponents and she can evade counter attacks. Her combos are elaborate, strong and even lethal which is something to watch out for. Her chain throw is difficult to perform and requires precision and patience.

Both sisters admired their father which has caused a intense rivalry between the two when they crave and compete for his attention. Then their father dies and the sisters have started to give the blame to each other for causing the dead of their father Richard. Their father's last wish is to maintain their relationship, but that made their rivalry heavier.

Nina's knowledge of assassination martial arts helps her quickly to become an assassin when she was twenty years old. Mishima Zaibatsu is the organisation of fight tournament The King of Iron Fist where a select group of fighters compete. She is hired to kill the head of the tournament a man named Heihachi Mishima. She participates at the tournament while she fails to kill Heihachi. 

Two years later, Nina is hired again to kill the current head of Mishima Zaibatsu a man named Kazuya Mishima by competing at The King of Iron Fist Tournament 2. She was captured by Kazuya after she has failed to assassinate him and was used as test subject for the "cold sleep" project of Dr. Boskonovitch, which does a cryogenic experiment on her. Anna Williams wants also to be put in cryogenic sleep as volunteer and she demands to wake up at the same time as Nina. The experiment has a duration of 19 years.

Nina suffers with heavy amnesia after she awakes from the cryogenic sleep, a fate which her sister Anna is spared. She is controlled by the recently awakened Ogre who the God of Fighting is. He sends her to take part in The King of Iron Fist Tournament 3 in order to kill Jin Kazama, who the grandson is of Heihachi Mishima. Jin makes her free from the control of Ogre and brings her senses back near the end of the tournament.

Anna worked intensively with Dr. Boskonovitch in order to bring the memories of her sister back as act of compassion. The project fails when Nina remembers that she can not get along with her sister. Nina leaves to a unknown destiny and has no contact with Anna for some time. Nina revives soon her role as assassin and that's the only thing which she can remember to her previous life. Two years later, she was contracted by a Mafia syndicate in order to kill famous British boxer Steve Fox. She discovers that Steve her biological son is, who was born through in vitro fertilisation during her years in cryosleep. Nina abandons her assassination attempt, after the syndicate is stopped by detective Lei Wulong at the last moment. She has no more a viable reason to pursue her targets after the collapse of her employers.

She remained emotionally impassive about the discovery of her biological son and shows itself otherwise for some, because she did not kill him when the chance was presented. Nina decides that it's time to discover her lost memories and comes to the conclusion that the only person who can help her is sister Anna Williams. The sisters meet after a while and Nina her hatred memories to her sister come back also. Later they meet again at The King of Iron Fist Tournament 5 where the sisters are engaged in a gun battle. The duo have plans to finish their battle for once and for all and the sisters promise that only one of them walks away after the battle. Nina wins the battle but refuses to kill Anna because she was not satisfied with the fight.

The CEO of Mishima Financial Empire Jin Kazama approaches Nina in order to become his personal bodyguard, because he has launched a war around the world. She competes at The King of Iron Fist Tournament 6 to intercept any possible threat against  him. Anna becomes the personal bodyguard Kazuya Mishima in order to take revenge against Nina, knowing that she comes face to face with Nina during the tournament.