Prewett family

"No one lived after he decided ter kill 'em, no one except you, an' he'd killed some of the best witches and wizards of the age — the McKinnons, the Bones, the Prewetts — you were only a baby an' you lived."

- The numerous wizards murdered during the first war

Prewett was the surname of a pure-blood wizarding family, and one of the Sacred Twenty-Eight. They were related to the Black, Weasley, and Macmillan families. With the deaths of Fabian and Gideon in the First Wizarding War, the status of the Prewett family is unknown, though it continued in the female line through the children of Molly Weasley.

Family history
Some members of the Prewett family would likely have been labelled "blood traitors", as they were members of the Order of the Phoenix and did not believe in the ideology of blood purity. However, the attitude of the prejudiced House of Black towards the Prewetts suggests that not all members were considered blood traitors. Lucretia Black was not disowned for marrying Ignatius Prewett, implying that the Prewetts were more accepted in elite pure-blood circles than a family like the Weasleys.

Distinctive family traits included red hair and large noses.

It is unknown whether Molly's second cousin (a squib accountant) was a pure-blood or not; he could have had a Muggle mother.

Etymology
The surname Prewett is Welsh in origin. It is derived from the Middle English word prou, meaning "brave" or "valiant", and the suffix "-et", which implies smallness. Thus, it is believed to be derived from a nickname for someone small, but brave.