The progressive leader known for founding Planned Parenthood is Margaret Sanger. She was a strong advocate for women's reproductive rights and played a crucial role in the birth control movement in the early 20th century. Sanger's efforts focused on providing women with access to birth control and education about sexual health. By establishing Planned Parenthood in 1916, she aimed to empower women to make informed choices regarding their bodies and reproductive health. Her work significantly contributed to the ongoing fight for gender equality and reproductive rights.