The Harry Potter series has many wizarding families as part of its canon: Weasleys, Malfoys, Potters, Longbottoms, Scamanders, Lestranges, etc. The most significant families might arguably be those descended from Salazar Slytherin because they had such a significant impact on the Wizarding World. Slytherin's line stops with the end of male heirs, but evidence is available to track the family's descendants from the present day back over a thousand years.
10th Century: Salazar Slytherin Is Born And Founds Hogwarts
11th Century: Salazar Slytherin Creates The Chamber Of Secrets And Departs From Hogwarts
13th Century: Cadmus Peverell Creates The Deathly Hallows With His Brothers, And The Family's Bloodline Intermarries With The SlytherinsPhoto: Harry Potter and the Deathly Hallows - Part 1 / Warner Bros. Pictures
16th-17th Centuries: Gaunt Family Members Become The Final Descendants Of SlytherinPhoto: Harry Potter and the Half-Blood Prince / Warner Bros. Pictures
1620-1635: Isolt Sayre Flees Gormlaith Gaunt And Founds Ilvermorny SchoolPhoto: Fantastic Beasts and Where to Find Them / Warner Bros. Pictures
18th Century: Corvinus Gaunt Seals The Chamber Of Secrets