AGE 28: Lady Gaga

Grammy Award-winning musician

What makes her powerful: The Mother Monster beat chart-topping artists such as Rihanna, Justin Bieber, and Taylor Swift to become the second-highest-paid musician. Lady Gaga reeled in $80 million last year, a figure that would have been higher had an injury not cut her Born This Way Ball Tour short.

She's an outspoken advocate for LGBT equality, marching in Pride parades and launching a nonprofit anti-bullying organization.