DoubleClick Inc. was an American advertisement company that developed and provided Internet ad serving services from 1995 until its acquisition by Google in March 2008. DoubleClick offered technology products and services that were sold primarily to advertising agencies and mass media, serving businesses like Microsoft, General Motors, Coca-Cola, Motorola, L'Oréal, Palm, Inc., Apple Inc., Visa Inc., Nike, Inc., and Carlsberg Group. The company's main product line was known as DART (Dynamic Advertising, Reporting, and Targeting), which was intended to increase the purchasing efficiency of advertisers and minimize unsold inventory for publishers.

DoubleClick was founded in 1995 by Kevin O'Connor and Dwight Merriman and had headquarters in New York City, United States. It was acquired by private equity firms Hellman & Friedman and JMI Equity in July 2005. On March 11, 2008, Google acquired DoubleClick for $3.1 billion. In June 2018, Google announced plans to rebrand its ads platforms, and DoubleClick was merged into the new Google Marketing Platform brand. DoubleClick Bid Manager became Display and Video 360, DoubleClick Search became Search Ads 360, and DoubleClick for Publishers (DFP) became Google Ad Manager 360.