In 2008, The X Factor winner Leona Lewis backed up her U.K. singing competition victory with an R&B anthem for the ages: "Bleeding Love," an international hit that became the best-selling song of the year. The track was co-penned by OneRepublic's Ryan Tedder (whose radio dominance would continue with songs such as Beyonce's "Halo" and Adele's "Rumour Has It") and solo artist Jesse McCartney, who was inspired by a former girlfriend, Gossip Girl actress Katie Cassidy. Given the song's success, McCartney didn't regret handing over such a personal track: "No, no," he said. "I'm so happy for Leona. She deserves it. There are really no bad feelings."