William Morris Jr., 90, son of the founder of the William Morris Agency and a former director and president of that entertainment talent group. He was born in 1899, the year his father started the agency, and began working there in 1918. He came to Los Angeles in 1930 and helped bring the Morris group into films. When his father died in 1932, Morris returned to New York and became president of the agency, holding the job for 19 years. In Malibu on Nov. 3.