The Queen and JK Rowling are the only British women to appear in the World’s 100 Most Powerful Women list, in 40th and 93rd place respectively.
Brazilian president Dilma Rousseff is second, and Melinda Gates, co-chairman of the Bill & Melinda Gates Foundation, is third in the list which, although international, is dominated by Americans.
The tenth annual ranking sees the Queen, who at 87 is the oldest on the list, drop 12 places from last year, while US First Lady Michelle Obama, who was number one in 2010, moves up three places from last year to fourth place.
According to Forbes, this year’s index represents women who are pioneers in politics, business, media, humanitarian concerns, entertainment and the technology industry. It also features a number of women who are listed due to their wealth, with all ranked by money, media presence and impact.
The top figures in the entertainment industry are Americans – Beyonce Knowles in 17th place, Angelina Jolie in 37th, and Lady Gaga in 45th after dropping 31 places.
From Australia, the country’s richest woman Gina Rinehart, the executive chairman of Hancock Prospecting, is the highest placed at number 16 while prime minister Julia Gillard comes in at number 28.
Mrs Merkel makes her eighth appearance on the list, while former US secretary of state Hillary Clinton, who was second last year, drops down to fifth.
Moira Forbes, president and publisher of ForbesWoman, said: “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.
“Whether leading multi-billion-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.”
The top women in technology are Facebook chief operating officer Sheryl Sandberg in sixth place, IBM chief executive Virginia Rometty in 12th, Hewlett-Packard chief executive Meg Whitman in 15th and Yahoo! chief executive Marissa Mayer in 32nd.
The women, who are from 26 countries, have 153 million Twitter followers between them.
There were 15 newcomers this year, including South Korean president Park Geun-hye in 11th place.