How did Salazar Slytherin die?
That wasn't mentioned in any of the books.
He is the great great grandfather, or maybe even more? We know that Tom Riddle's grandfather is Marvolo Gaunt. (Another reply) According to the story, Salazar Slytherin lived about 1000 years ago. Thus, although Marvolo Gaunt was descended from Slytherin, it was far more than 2 generations. Something like 30-50 generations, perhaps.
Salazar Slytherin, in the Harry Potter series, is one of the four founders of Hogwarts. He and Godric Gryffindor, Helga Hufflepuff, and Rowena Ravenclaw helped build the school, but Slytherin and the others fell out, Slytherin pronouncing that the school should only be for pure-bloods, wizards born of wizards for generations, the others saying that Hogwarts should be for everybody, and soon, Slytherin built a chamber within a school, letting inside it a terrible monster…