Business magazine Forbes has named German chancellor Angela Merkel the most powerful woman in the world, for the third successive year. In addition, Merkel has made it to the list eight times in the past decade; seven of those were at No 1.

Brazilian president Dilma Rousseff is second and Melinda Gates, Microsoft founder Bill Gates' wife and co-chairman of the Bill & Melinda Gates Foundation is third.

Michelle Obama, US president Barack Obama's wife, who was No 1 in 2010, has slipped to fourth. Hillary Clinton, the former US Secretary of State and wife to former US president Bill Clinton, is fifth.

The Queen and Harry Potter author JK Rowling were the only British women to appear in the top 100. The 87-year-old monarch, who is the oldest on the list, dropped from 26 to 40 and 47-year-old Rowling fell from 78 to 93.

2013 saw 15 debutants on the list, including South Korea's first female president, Park Geun-hye. Also making their first appearances are Italian physicist Fabiola Gianotti (one of the scientists at the CERN Large Hadron Collider and co-discoverer of the Higgs boson particle) and the world's youngest self-made female billionaire, Sara Blakely (the owner of undergarment company Spanx).

The list included women from seven categories - technology, business, media, entertainment, non-profit organisations and politics. The women had a combined Twitter following of more than 153 million people.

"This year's Power Women exert influence in very different ways, and to very different ends, and all with very different impacts on the global community," Moira Forbes, president and publisher of Forbes Woman, said, "Whether leading multibillion-dollar companies, governing countries, shaping the cultural fabric of our lives or spearheading humanitarian initiatives, collectively these women are changing the planet in profoundly powerful and dynamic ways."

Check out the top ten women on the Forbes' Most Powerful Women in the World list