Which athlete has won the most IAAF (International Association of Athletics Federations) World Championship medals?

Allyson Felix is the most decorated athlete in IAAF World Championships history with 16 career medals. In four events she has won 11 gold, three silver and two bronze medals

Felix (born November 18, 1985) is an American track and field sprinter who competes in the 100 meters, 200 meters, and 400 meters. At 200 meters, she was the 2012 Olympic champion, a 3-time World champion (2005–09), and 2-time Olympic silver medalist (2004–08). At 400 meters, she was the 2015 World champion, 2011 World silver medalist, 2016 Olympic silver medalist, and 2017 World bronze medalist.

She has won five additional Olympic gold medals as a member of the United States' women's relay teams: three at 4 × 400 meters (2008–16), and two at 4 x 100 meters (2012–16). The 2012 U.S. Olympic 4 x 100 meters team which set the women's 4x100 meters world-record. Felix is the only female track and field athlete to ever win six Olympic gold medals, and is tied with Merlene Ottey as the most decorated female Olympian in track and field history, with a total of nine Olympic medals.