Tonks left Hogwarts in the summer of 1991 and began three years of Auror training. Not surprisingly, she passed her Concealment and Disguise exam effortlessly but had difficulty with Stealth and Tracking. She qualified as an Auror in 1994, one year before her first appearance in the Order of the Phoenix.

Tonks is a born Metamorphmagus, which means that she can change her appearance at will. In Order of the Phoenix, Tonks explains that "Metamorphmagi are really rare, they're born, not made." She does not, however, indicate whether the trait is a hereditary characteristic or a random mutation. So far, none of Tonks's relatives are known to be Metamorphmagi. Although her features can change, her natural appearance is that of a pale-skinned young woman with heart-shaped face, dark eyes (courtesy of her Black heritage), and brown hair. She first appeared with purple hair in the fifth book, and later changed it to bubble-gum pink.

Tonks is introduced as an Order member and secondary character in Order of the Phoenix. At the time, she and a slightly senior Auror, Kingsley Shacklebolt, were covert spies in the Ministry. Indiscreet action would have cost them their positions due to the prevailing (and misguided) anti-Dumbledore policy, but they were able to supply intelligence.

Tonks fought the Death Eaters at the Department of Mysteries together with Alastor Moody, Sirius Black, Remus Lupin and Kingsley Shacklebolt. She was injured by her aunt, Bellatrix Lestrange, and despite Moody's ministrations had to be taken to St. Mungo's hospital. She was fully healed and released, and a short time later got together with Alastor Moody, Remus Lupin and some of the Weasleys to confront Vernon Dursley about Harry's treatment at Number Four Privet Drive.

During Harry Potter and the Half-Blood Prince, Tonks was stationed at Hogsmeade and assigned to guard Hogwarts. Harry observed her behaving uncharacteristically: she was constantly depressed, rarely smiling or being friendly as she had previously been. Her hair had reverted to a mousy brown, apparently its natural colour, suggesting that her Metamorphosing had been disturbed, and her Patronus changed some time after the battle from its original form to a large, hairy, four-legged creature. Such changes were held to be evidence of extreme shock or strong emotions. Harry and his friends assumed that her evident depression was due to the death of her cousin Sirius Black; she may have felt responsible for Sirius's death, as she had dueled with Bellatrix Lestrange first, but had been incapacitated by her, thus leaving Bellatrix free to murder Sirius. Harry even speculated that Tonks might have been in love with Sirius - not the least since her Patronus resembled Sirius' Animagus form.

After Albus Dumbledore's death, it was revealed that Tonks was in fact pining for Remus Lupin, who perversely insisted that he was "too old . . . too poor . . .[and] too dangerous" for her. Many fans now believe that Tonks's new Patronus is a werewolf and that her hair may have turned mousy as a reflection of her weakened Metamorphosing powers. At Dumbledore's funeral at the end of Half-Blood Prince, Tonks and Remus were seen holding hands and her hair was once again pink, suggesting that her depression had passed.

When she travels with the Order to pick up Harry before his seventeenth birthday, she is extremely happy to show off her wedding ring. She and Lupin had a quiet wedding, and is recently pregnant. Tonks realized that her aunt Bellatrix seems dead set on killing her, but manages to escape Bellatrix's attack while they are getting Harry to safety.

Tonks gives birth to a son, Ted Remus Lupin, who seems to be a metamorphmagus like her.

She leaves Teddy in the care of her mother, Andromeda, and arrives at Hogwarts to help in the fight. She shows extreme concerned for Remus and runs off to find him when she hears he was fighting Dolohov. Her body is seen next to Remus by Harry in the Great Hall, and JK Rowling revealed that it was indeed, Bellatrix who killed her.

Interesting Facts
Spouse: Remus Lupin
Children: Teddy Lupin
Occupation: Auror (Qualified in 1994, but nearly failed on the Stealth & Tracking)
Appearance: Pretty, with a pale, heart shaped face.
Hair: Varies in style and color (Pink, Violet, Brown...)
Eyes: Varies in color, described as dark and twinkling
Blood Type: Half-blood
Hogwarts House: Hufflepuff (1984-1991)
Allegiance: Order of the Phoenix
Music: Fan of the Weird Sisters
Patronus: While her first Patronus is unknown, her current Patronus is a large, four-legged creature (allegedly a werewolf).
Death: By Bellatrix Lestrange - May of 1998
Film Portrayer: NATALIA TENA

- Source: WIKIPEDIA