Daphne Greengrass is a pure-blood witch, the eldest daughter of clothing mogul Asbolus Greengrass and Hemera Greengrass. She has a sister, Astoria, who is younger by two years. She began attending Hogwarts School of Witchcraft and Wizardry in 1991, the same year as Harry Potter, and was sorted into Slytherin and shared a dormitory in Slytherin Dungeon with Pansy Parkinson, Millicent Bulstrode, and Tracey Davis. She was a member of the short-lived Inquisitorial Squad in early 1996. She took her O.W.L.s in 1996 at the same time as Hermione Granger.
Daphne and Dean Thomas started dating in early 1994. They broke up, after Dean kissed Daphne while she was wearing watermelon lip gloss, which he hated.
In the spring of 1996, Daphne was one of the members of the Inquisitorial Squad, formed by then-Headmistress Dolores Umbridge due to a need for extra credit as her grades had recently begun to slip. She was one of the students that saw Fred and George Weasley flying away from school. At the end of the school year, the Inquisitorial Squad was disbanded when Albus Dumbledore returned.
When Harry Potter returned, Daphne chose to fight against Voldemort and his army. She, along with Tracey and the other members of Slytherin House who chose to stay, fought in the Battle of Hogwarts. While Daphne was defending the hall, Tracey was killed immediately by a Death Eater. Daphne avenged her friend's death by casting a spell to allow her to escape with Tracey's body. After the battle ended, Daphne placed Tracey's body with the others. She was later seen talking with Tracey's parents after the battle had ended.
Daphne never married, although she adopted a girl named Verga, named after the Virgo star sign.
Daphne is known in certain circles of pure-blood society as a blood-traitor for her moderate views towards muggles and muggle-borns. However, Daphne never speaks unless it is necessary with anyone other then her long time friend Tracey. Daphne is known to wear a calm yet intimidating look in public. Privately, Daphne has a passion for fashion, musicals, and books. Despite her family's wealth neither Daphne nor her sister Astoria saw any reason to hold this over anyone's head.