Simplify the following text for a Grade 10 native English-speaking person.
Original: Jeffery John `` Jeff '' Hanneman ( born January 31 , 1964 ) is an American musician He is most famous for being one of the founding members of the thrash metal band Slayer .
Simplified: Jeffrey John `` Jeff '' Hanneman ( born January 31 , 1964 ) is best known as one of the guitarists as well as a founding member of the American thrash metal band Slayer .