Chaim Potok was an ordained rabbi, and an acclaimed writer of fiction. His favorite subjects were the spiritual and cultural life of orthodox Jews. A few of his more notable books were The Chosen, the Promise, and My Name Is Asher Lev.
He died in 2002.
His signature is worth in the $15 - $25 range. His signature on one of his books is worth more, depending on the value of the book.