Pfizer Incorporated ( ) is a major pharmaceutical company, which ranks number one in sales . The company is based in New York City. It produces the number-one selling drug Lipitor (atorvastatin, used to lower blood cholesterol); the neuropathic pain/fibromyalgia drug Lyrica (pregabalin); the oral antifungal medication Diflucan (fluconazole), the long-acting antibiotic Zithromax (azithromycin), the well-known erectile dysfunction drug Viagra (sildenafil citrate), and the anti inflammatory Celebrex (celecoxib) (also known as Celebra in some countries outside USA and Canada, mainly in South America).

Pfizer's shares were made a component of the Dow Jones Industrial Average on April 8, 2004.

With 2005 actual spending of $7.4 billion in research & development (R&D), Pfizer boasts the industry's largest pharmaceutical R&D organization: Pfizer Global Research and Development.