Ornella Barra

Previously an executive with Alliance Boots, Barra’s responsibilities grew considerably with the official creation of Walgreens Boots Alliance in December 2014. The supersized pharmacy chain—Barra helped lead the integration of the two companies—has 370,000 employees and a market cap of $96 billion. Barra’s role at the new company, which is headed by her partner Stefano Pessina, is likewise staggering: she runs the pharmaceutical wholesale business, which spans 19 countries and a network of 200,000 some pharmacies and healthcare providers, as well as international retail. She’s also now spearheading Walgreen Boots Alliance’s corporate social responsibility efforts and supervises global communications. —Erika Fry