Democratic presidential candidate Hillary Clinton is right behind Merkel, taking the No. 2 slot. Clinton, according to Forbes, has placed on the list every year since its inception in 2004.
The 2015 list also features newcomer Taylor Swift, at the age of 25 the youngest on it, placed at No 64.
However top ranked in the entertainment industry is Beyoncé, whose On The Run joint tour with her husband, Jay Z, grossed more than £100m last year.
The Forbes list is compiled using the criteria of money, media momentum, spheres of influence and impact.
Here are the Top 25:
1. Angela Merkel, German chancellor
2. Hillary Clinton, U.S. presidential contender for 2016
3. Melinda Gates, co-chairwoman for the Bill & Melinda Gates Foundation
4. Janet Yellen, chairwoman for the U.S. Federal Reserve Bank
5. Mary Barra, CEO of General Motors
6. Christine Lagarde, managing director for the International Monetary Fund
7. Dilma Rousseff, Brazilian president
8. Sheryl Sandberg, COO of Facebook
9. Susan Wojcicki, CEO of Youtube
10. Michelle Obama, U.S. first lady
11. Geun-hye Park, South Korean president
12. Oprah Winfrey, media mogul
13. Virginia Rometty, CEO of IBM
14. Meg Whitman, CEO of HP
15. Indra Nooyi, CEO of Pepsico
16. Cristina Kirchner, Argentinean president
17. Irene Rosenfeld, CEO of Mondelez
18. Ana Botin, chairman of Banco Santander
19. Abigail Johnson, CEO of Fidelity Investments
20. Marillyn Hewson, chairwoman of Lockheed Martin 21. Beyonce Knowles, entertainer and entrepreneur
22. Marissa Mayer, CEO of Yahoo
23. Helen Clark, administrator or the United Nations Development Programme
24. Safra Catz, co-CEO of Oracle
25. Angela Ahrendts, senior vice president of Apple.... reuters