Joanna Sue Zeiger (born May 4, 1970) is an American triathlete who is the 2008 Ironman 70.3 world champion.

[2] Zeiger was born in Baltimore, Maryland, grew up in San Diego, California,[3][4] lives in Boulder, Colorado, and is Jewish.

She and her sister, Laurie, represented the United States at the 1989 Maccabiah Games, the Jewish Olympics, in swimming.

Zeiger received her PhD from Johns Hopkins University's Bloomberg School of Public Health in 2001.

In 2008, Zeiger won the Ironman 70.3 World Championship in Clearwater, Florida with a time of 4:02.49.