It used to be enough for a celebrity to act or sing or swing a bat really well. Now to be considered a real success, he or she needs to sell clothes, hawk fragrances--maybe even invest in technology startups. 
 
 While she hasn’t stormed Silicon Valley just yet, Jennifer Lopez is a state-of-the-art celebrity success story. With $52 million in earnings over the last 12 months and a massive amount of fame, Lopez lands at No. 1 on our Celebrity 100 list for the first time. 
 
 A few years ago it looked like Lopez was done. Her albums, like the all-Spanish Como Ama una Mujer, failed to find the broad audience she once enjoyed. Her movies, like El Cantante, flopped. 
 
 Then in 2010 the singer landed a judge's chair on American Idol. The job gave her a platform to promote her music and turn her image around. It didn’t hurt that she also split from her husband, Marc Anthony. Suddenly a single mother, Lopez lapped up the media attention and scored lucrative endorsement deals with companies like L’Oreal and Gillette. She now has a line of clothing at Kohl's, a top-selling fragrance and she was able to secure a nice bump—to $20 million--on her Idol salary for a second season. With 6.6 million followers on Twitter and 12 million fans on Facebook, she’s also proved a master of social media. 
 
 Lopez unseats Lady Gaga, who topped the list last year. The pop star slides to fifth place this time around with $52 million in earnings, down from $90 million last year (Gaga didn’t tour much in the last 12 months). Her new album, Born This Way, was still a smash hit, selling 1 million copies its first week out. 
 
 Cover Story: Justin Bieber, Venture Capitalist 
 
 In second place is Oprah Winfrey, whom Gaga unseated for No. 1 last year. Winfrey had a rough 12 months. Her 25-year syndication run ended in May but she still managed to earn more than anyone else on the list ($165 million) thanks to her empire of spin-off shows (Dr. Phil, Rachael Ray) her magazine and her radio deal with Sirius XM. Winfrey doesn’t earn any money from the struggling OWN cable network. The talk-show legend will now turn her full attention to trying to improve things at OWN. 
 
 Ranking third: Justin Bieber. Only 18, Bieber is making his second appearance on our list. The star earned $55 million in the past year thanks to touring and record sales, but as he explains in our cover story, Bieber is more than just a pop star. He’s also a budding venture capitalist. Bieber has used his fame and fortune to invest in startup companies like Spotify, Tinychat and Enflick. 
 
 With most of our lists we keep it strictly on the money: earnings or net worth. The Celebrity 100 is a little different. This list--which includes film and television actors, TV personalities, models, athletes, authors, musicians and comedians--is based on money and fame. We define fame as media visibility in print, television, radio and online, plus social media power, which we measure by looking at each celebrity's presence on Facebook and Twitter. The earnings consist of pretax income between May 1, 2011, and May 1, 2012. Management, agent and attorney fees are not deducted. Forbes has been publishing the list annually since 1999. 
 
 Crunching all those numbers always ensures we have an interesting slew of new people on the list; this year, Kim and Khloe Kardashian made the cut. Say what you want about the sisters, they know how to stay famous and earn millions. Thanks to the money she earned from her wedding (and the publicity she earned from her divorce just a few months later), Kim ranks seventh with $18 million. Khloe, who now has her own successful spin-off show (Khloe and Lamar), ranks 73rd with $11 million. 
 
 Another newcomer: Ashton Kutcher. The actor, who took over the lead on Two and a Half Men following Charlie Sheen’s very public meltdown, is now one of the highest-paid men on television. (Sheen failed to make the list this year.) He’s also a savvy tech investor who managed to get in early on companies like Skype, Spotify and Airbnb, which is now worth a reported $1 billion. Kutcher, who is a Twitter superstar, got plenty of press attention this year for his personal life as well as his professional life. He split from his wife of six years, Demi Moore, last fall. The actor debuts in 51st place with $24 million. 
 
 Full List: The Celebrity 100 
 
 Follow me on Twitter at DorothyatForbes. ||||| The men and women on our annual Celebrity 100 list--the most powerful people in the entertainment business this year--earned $4.5 billion over the last 12 months by starring in films, playing basketball, walking the catwalk and more. But they also rose to the top by garnering influence. 
 
 These days that means mastering social media. Lady Gaga topples Oprah Winfrey from her No.1 spot on our list, which she's given up for only the third time in seven years. Gaga is there not just because of the $90 million she earned with a monster tour, but also because of her 32 million Facebook fans and 10 million Twitter followers--aka Little Monsters--who helped move 1 million digital downloads of her recent single "Born This Way" in only five days. They're also happy to buy the MAC makeup, Monster headphones and Virgin Mobile phones she features in her videos. 
 
 Complete Coverage: The Celebrity 100 
 
 Slide Show: The Celebrity 100 In Pictures 
 
 Oprah doesn't fall far though. The daytime talk maven, who earned $290 million last year, comes in second. Winfrey's earnings sank $25 million partially due to a reduced payday at SiriusXM. She still earns big from her syndicated show and from the stars she's spawned, including Dr. Phil (No. 18) Rachael Ray and Dr. Oz. Winfrey's earning power will take a bigger hit next year, when her syndicated show ends and she concentrates all her efforts on the struggling OWN network. 
 
 Maybe it would help if Oprah took a lesson from No. 3 Justin Bieber. The Biebs debuts on our list at the tender young age of 17, with $53 million earned over the last 12 months thanks to concerts, music sales and a 3-D documentary movie that grossed $100 million at the global box office. If this were 10 years ago Bieber would still be paying his dues in small clubs and schools, but thanks to the Internet, he's a sensation. His first hit song, "Baby," has been viewed 500 million times, a YouTube record. 
 
 Reality TV it girl Bethenny Frankel is another newbie worth noting. Famous for her newest hit show, Bethenny Ever After, she's used the small-screen platform to promote her Skinnygirl brand, helping her earn $55 million this year. She joins our list in 42nd place. Her entrepreneurial prowess--she sold her Skinnygirl Cocktails to Fortune Brands and nabbed a $100 million cut of the deal paid out over multiple years--also put her on the cover of our magazine this week. 
 
 The Celebrity 100, which includes film and television actors, TV personalities, models, athletes, authors, musicians and comedians, is a measure of entertainment-related earnings and media visibility (exposure in print, television, radio and online). We also measure social media power by looking at each celebrity's presence on Facebook and Twitter. The earnings consist of pretax income between May 1, 2010, and May 1, 2011. Management, agent and attorney fees are not deducted. Forbes has been publishing the list annually since 1999. 
 
 Despite problems on and off the golf course, Tiger Woods still makes the top 10, ranking sixth with $75 million in annual earnings. Woods hasn't won a tournament since the revelation of his marital infidelities in 2009, and he recently withdrew from The Players Championship. But he still commands $3 million a pop for overseas appearances, and collects money from his remaining sponsors, Nike and Electronic Arts . 
 
 Having a much better year: Leonardo DiCaprio. The star makes the biggest leap on our list this year, rising from 71st place to 15th, thanks to two huge movies: Shutter Island and Inception. The latter earned $825 million at the global box office, making it the sixth-highest-earning film of 2010. That went a long way toward helping DiCaprio earn $77 million over the last 12 months. 
 
 Will Smith returns to our list this year thanks to the upcoming Men in Black III, in which he'll reprise his role as Agent J. Smith had fallen off of our list in 2010 because he took time off to nurture the budding careers of his children, Jaden and Willow. Jaden starred in a remake of The Karate Kid (which Smith produced); the film earned $360 million. Smith helped Willow with her hit song "Whip My Hair." The video for the song has been viewed 11 million times. 
 
 Notable drop-offs include Britney Spears, who ranked sixth in 2010 but stumbled this year because she didn't tour. With the Harry Potter franchise coming to an end, Daniel Radcliffe (who ranked 82nd last year) also failed to make the cut. 
 
 Complete Coverage: The Celebrity 100 
 
 Slide Show: The Celebrity 100 In Pictures
– Jennifer Lopez went from superstar to has-been … and has now apparently swung back to superstar. The American Idol judge tops the latest Celebrity 100, Forbes’ annual list of the stars with the most money and fame, with $52 million in earnings over the past year. In addition to her new Idol gig, she’s gotten quite a bit of publicity thanks to her divorce, big endorsement deals, a clothing line and fragrance, and tons of fans and followers on social media. Last year’s No. 1, Lady Gaga, is all the way down in fifth place, while Oprah Winfrey—who was No. 1 the year before Gaga—is No. 2 this year. (But Oprah didn’t make it on Time’s Most Influential People list for the first time ever this year.) Here’s the full top 10, which may make you a little bit sad if you're not 13 years old: Jennifer Lopez Oprah Winfrey Justin Bieber Rihanna Lady Gaga Britney Spears Kim Kardashian Katy Perry Tom Cruise Steven Spielberg See Forbes for all 100.