In sixteenth-century Brazil, several European women governed the captaincies of their late or absent husbands during the first century of Portuguese colonization. A contextual and lexical analysis of the male-authored sources reveals that these women acted decisively to protect and expand familial patrimonies and, in doing so, were part of the colonizing movement. Although extensive written evidence survives that attests to their authority and agency over colonial affairs, their importance has been overlooked in the scholarship. Therefore, this essay argues that a small group of elite European women became imperial agents who wielded power against colonial subjects in select circumstances.