Joan Blades (b. ca. 1956 in Berkeley, California) was the cofounder in 1987 with her husband Wes Boyd of Berkeley Systems, a San Francisco Bay area software company known for marketing the After Dark screensaver and the You Don't Know Jack trivia game. After selling Berkeley Systems in 1997 for $13.8 million, Blades and Boyd founded the liberal political group MoveOn.org.

She received her BA in History from UC Berkeley in 1977 and her J.D. from the Golden Gate University School of Law. She was an attorney in Alaska and California, taught mediation at Golden Gate University, wrote a book Mediate Your Divorce (published by Prentice Hall), and co-wrote The Divorce Book. She met her future husband, a computer programmer, when the two were playing recreational soccer in the 1980s. She was a member of the board at Berkeley Systems and its Vice President of Marketing. Joan created many of the box designs for the early Berkeley Systems products such as Stepping Out and After Dark based on her original collage-art.

Since May 2005, she has been a contributing blogger at The Huffington Post.

More recently, Blades, along with Kristin Rowe-Finkbeiner, founded the organization MomsRising, dedicated to "bringing millions of people, who all share a common concern about the need to build a more family-friendly America, together as a non-partisan force for 2008 and beyond." Currently, MomsRising has a base of 122,000 people and is growing at the rate of 500-1000 new members a week.