Co-COO, Walgreens Boots Alliance, 62
Barra earned another promotion in June—her third in three years—to co-COO of Walgreens Boots Alliance, the $103 billion global pharmacy chain that is run by her partner Stefano Pessina. (Though the recently merged, much-enlarged entity is based in Chicago, Barra, who oversees, among other things, international retail and global brands, is based in Europe.) Indeed, the scope of Barra’s responsibilities is vast: she also leads the company’s Pharmaceutical Wholesale division—which extends to 200,000 healthcare providers in 19 countries—as well as supply chain, communications, HR and IT functions. Barra, an Italian who began her career as a pharmacist, built her own small business before merging it with Pessina’s in the 1980s. They kept building—and hundreds of deals later, their company ranks No. 47 on Fortune’s Global 500.