Lady Gaga performs

(Photo credit should read FILIPPO MONTEFORTE/AFP/Getty Images)

#1: Lady Gaga is the highest-paid celebrity under the age of 30, according to the latest ranking from Forbes. The 25-year-old took home $90 million this past year. (Photo credit should read FILIPPO MONTEFORTE/AFP/Getty Images)

2011 CMT Music Awards - Arrivals

(Photo by Jason Merritt/Getty Images)

#2: Justin Bieber (age 17) earned $53 million. (Photo by Jason Merritt/Getty Images)

Miami Heat v Dallas Mavericks - Game Five

(Photo by Garrett Ellwood/NBAE via Getty Images)

#3: Miami Heat's LeBron James (age 26) earned $48 million. Copyright 2011 NBAE (Photo by Garrett Ellwood/NBAE via Getty Images)

Switzerland's Roger Federer reacts as he

(Photo credit should read PATRICK KOVARIK/AFP/Getty Images)

#4: Tennis star Roger Federer (age 29) earned $47 million. (Photo credit should read PATRICK KOVARIK/AFP/Getty Images)

2011 Billboard Music Awards - Arrivals

(Photo by Isaac Brekken/Getty Images)

#5: Singer Taylor Swift (age 21) earned $45 million. (Photo by Isaac Brekken/Getty Images)

2011 Logie Awards - Arrivals

(Photo by Ryan Pierse/Getty Images)

#6: Katy Perry (age 26) earned $44 million. (Photo by Ryan Pierse/Getty Images)

Real Madrid v UD Almeria - La Liga

(Photo by Denis Doyle/Getty Images)

#7: Real Madrid soccer star Cristiano Ronaldo (age 26) earned $38 million. (Photo by Denis Doyle/Getty Images)

2011 Billboard Music Awards - Show

(Photo by Ethan Miller/Getty Images for ABC)

#8: Beyonce (age 29) earned $35 million. (Photo by Ethan Miller/Getty Images for ABC)

Barcelona's Argentinian forward Lionel Messi

(Photo credit should read FRANCK FIFE/AFP/Getty Images)

#9: Barcelona soccer star Lionel Messi (age 23) earned $32 million. (Photo credit should read FRANCK FIFE/AFP/Getty Images)

AEGON Championship - Day Five

(Photo by Julian Finney/Getty Images)

#10: Tennis star Rafael Nadal (age 25) earned $31 million. (Photo by Julian Finney/Getty Images)

2011 Billboard Music Awards - Show

(Photo by Ethan Miller/Getty Images for ABC)

#11: Rihanna (age 23) earned $29 million. (Photo by Ethan Miller/Getty Images for ABC)

Atlanta Hawks v Orlando Magic - Game Five

(Photo by Fernando Medina/NBAE via Getty Images)

#12: Orlando Magic center Dwight Howard (age 25) earned $28 million.
Copyright 2011 NBAE (Photo by Fernando Medina/NBAE via Getty Images)

Miami Heat v Dallas Mavericks - Game Five

(Photo by Ronald Martinez/Getty Images)

#13: Miami Heat's Dwyane Wade (age 29) earned $26 million. (Photo by Ronald Martinez/Getty Images)

"Alexander McQueen: Savage Beauty" Costume Institute Gala At The Metropolitan Museum Of Art - Arrivals

(Photo by Stephen Lovekin/Getty Images)

#14: New York Knicks' Carmelo Anthony (age 27) earned $25 million. (Photo by Stephen Lovekin/Getty Images)

Maria Sharapova

(Photo credit should read THOMAS COEX/AFP/Getty Images)

#15: Tennis star Maria Sharapova (age 24) earned $24 million. (Photo credit should read THOMAS COEX/AFP/Getty Images)

Miley Ray Cyrus

(Photo credit should read NORBERTO DUARTE/AFP/Getty Images)

#16: Miley Cyrus (age 18) earned $15 million. (Photo credit should read NORBERTO DUARTE/AFP/Getty Images)

2011 MTV Movie Awards - Arrivals

(Photo by Jason Merritt/Getty Images)

#17: Actress Kristen Stewart (age 21) earned $20 million. (Photo by Jason Merritt/Getty Images)

Water For Elephants Sydney Premiere

(Photo by Marianna Massey/Getty Images)

#18: Actor Robert Pattinson (age 25) earned $20 million. (Photo by Marianna Massey/Getty Images)

Fox's "American Idol" 2011 Finale - Results Show - Arrivals

(Photo by Frazer Harrison/Getty Images)

#19: Singer Carrie Underwood (age 28) earned $15 million. (Photo by Frazer Harrison/Getty Images)

Lil Wayne Performs His "I Am Still Music" Tour At The Staples Center

(Photo by Kevin Winter/Getty Images)

#20: Rap artist Lil Wayne (age 28) earned $15 million. (Photo by Kevin Winter/Getty Images)