Lynn Margulis

From EvoWiki

Lynn Margulis was the developer of the endosymbiotic theory that claims organelles in eukaryotes evolved from prokaryote organisms that had been ingested by larger cells and came to live symbiotically with them. Her theory (or hypothesis) was for several years rejected. But through the perseverence of Margulis and others, the theory is now widely accepted.

Margulis is also a supporter of the Gaia theory which was originally proposed by James Lovelock.