Complex sentence: Roy is best known for his portraits of celebrities, socialites, and personalities, which have appeared on the covers and pages of Vogue, Vanity Fair, GQ, Harper's Bazaar, and Rolling Stone.
Split into simpler sentences: Roy is best known for his portraits of celebrities, socialites, and personalities. His portraits have appeared on the covers and pages of Vogue, Vanity Fair, GQ, Harper's Bazaar, and Rolling Stone.