Trierweiler is the girlfriend of the Socialist Party's Francois Hollande, who won France's general election this weekend and who will step in as France's first Socialist president in nearly two decades, replacing conservative incumbent Nicolas Sarkozy. Sarkozy, of course, is married to supermodel-turned-songwriter Carla Bruni.
She'll also be the first unmarried French "first lady" in the country's history, and insists on being called Hollande's "companion" rather than his partner.
(Because the couple aren't married, Trierweiler can't technically be called the first lady of France. But Hollande has said that the pair won't be pulling a Sarkozy-style quickie wedding.) Here are five things to know about Trierweiler, 47, who's been dating Hollande since 2006:
#Nicknamed "The Rottweiler," she's a political journalist for Paris Match magazine, and she once reportedly slapped a colleague for saying something sexist.
#She's on Twitter!
#She reportedly helped Hollande drop over 20 pounds and served as his de facto image consultant, insisting he tone down his jokey, casual air and act more formal during speeches. Hollande has been mocked in the past for his "bland" and "wishy-washy" appearance.
#She claims Hollande does most of the shopping and cooking.
# Twice-divorced, she's a mom of three.