Jennifer Lopez is Forbes magazine’s most powerful celebrity. The American Idol judge topped the annual list, climbing up from the 50th spot last year. Last year’s number one, Oprah Winfrey dropped to number two, but was ahead of Justin Bieber (3), Rihanna (4) and Lady Gaga (5).Pop stars were big in the top ten with Britney Spears and Katy Perry also landing high spots on the list. Kim Kardashian was number seven.The list’s release coincided with another from The Hollywood Reporter, of the most powerful individuals in reality TV. Unsurprisingly, Ryan Seacrest topped that one, but came in at 29 on the Forbes countdown.Rihanna and Oprah have topped the Forbes 100 most powerful celebrities list. The rankings are determined by fame and money — and the star’s level of fame is calculated by their media visibility across all platforms. The magazine also takes into account the celebrity’s social media power. Rihanna came in at number 4 on the list, making $53 million in the past year. Although she didn’t earn as much as Oprah, her press, web and social media rankings were higher — scoring the number two spot on social media.Oprah is number two on the list, earning $165 million in the past year. O’s press rank was 13 out of 100, her web rank was 19 out of 100 and her overall social media presence was 18 out of 100.Jennifer Lopez came in at the top spot for the first time in her career. Other celebs on the list include, Tiger Woods at number 13, LeBron James at number 15, Beyonce at number 16 and Tyler Perryat number 20.