Lady Gaga is the new "World's Most Powerful Celebrity" according to Forbes magazine's annual "The Celebrity 100" list, knocking Oprah Winfrey to second place.  According to the magazine, Gaga tops the list this year not just due to her incredible earnings (she banked $90 million from her "Monster Ball" tour alone), but because of her powerful social media presence. Gaga is known for her incredibly dedicated fans, having a whopping 32 million Facebook fans and 10 million Twitter followers, who helped move 1 million copies of her hit single, “Born This Way,” in just five days.

But don't feel too bad for Oprah. The legendary talk show host earned $290 million last year – and that's a pay cut from the previous year, when she earned $25 million more.

Teen superstar Justin Bieber is a notable addition to the list, debuting at No. 3. The youngest member of the "Celebrity 100", he earned $53 million over the last year. But even more impressive than his multi millions? His song "Baby" has been viewed over 500 million times on YouTube, an impressive record yet to be topped.

Leonardo DiCaprio also has a reason to be happy with Forbes – he had the biggest climb this year, going from No. 71 all the way up to No. 15 due to huge box offices successes 'Shutter Island' and 'Inception'.

But by far it is the musicians who rule the 2011 list, with U2, Elton John, Taylor Swift and Bon Jovi all cracking the top 10.

According to Forbes, their celebrity power ranking is a measurement of entertainment-related earnings and media visibility (exposure in print, television, radio and online) over the past 12 months, as well as social media power.