As we've taken pains to point out, "Founding Father" is a pretty fluid term. And if we're generously including anyone with an early influence on the founding of America, we have every reason to put Abigail Adams on the list.
Adams is famous for advising her husband to "remember the ladies" as he helped form the United States government. But she went even farther than that, cautioning her husband that they "will not hold ourselves bound by any laws in which we have no voice, or representation" [source: American Experience]. Her letters are considered some of the earliest examples of modern feminist writing.
John Adams' wife wasn't just whispering in her husband's ear, however. She was also appointed by the Massachusetts Colony General Court to a panel charged with questioning women who had been accused of Tory sympathies or actions -- the first "political" appointment of a first lady [source: National First Ladies' Library].