The list was topped for the second year in a row by German Chancellor Angela Merkel, one of eight heads of state in the top 100.
The Queen, who marked her Diamond Jubilee this year, charted at number 26 - 12 places below pop star Lady Gaga at 14.
The top ten is dominated by political leaders, including US Secretary of State Hillary Clinton at number two and First Lady Michelle Obama at seven.
Christine Lagarde, the high-profile managing director of the International Monetary Fund (8) and Facebook executive Sheryl Sandberg (10) also chart highly.
In its introduction to the list, Forbes sets out the thinking behind the selections: “These are the women who adhere to the traditional classifications of power (political and economic might) and those who have risen to the top of the social and cultural landscape. It is our annual snapshot of women who impact the world.”
Marissa Mayer, another big name from the world of technology who recently made the switch from Google to become CEO at Yahoo, makes an appearance at 21.
Edinburgh-based Rowling, who charts at 78, amassed her fortune through the Harry Potter series of books, but Forbes make reference to her imminent move into adult fiction, and the recent successful launch of her online store Pottermore.
Aside from Lady Gaga, other stars from the entertainment world include Oprah Winfrey (11), Beyoncé Knowles (32), Jennifer Lopez (38) and Angelina Jolie (66) - most of whom were also listed as “philanthropists”.
Burmese politician Aung San Suu Kyi, who this year collected the Nobel Peace Prize she won in 1991 while under house arrest, featured at 19.
The full list is available at www.forbes.com/power-women