Andeavor (NYSE: ANDV), formerly known as Tesoro Corporation, or simply as Tesoro, is a Fortune 100 and a Fortune Global 500 company headquartered in Texas at San Antonio, with 2013 annual revenues of $37 billion, and over 13,000 employees worldwide.

Andeavor is an independent refiner and marketer of petroleum products, operating ten refineries in the Western United States with a combined rated crude oil capacity of approximately 1,200,000 barrels (190,000 m) per day. Andeavor’s retail-marketing system includes approx. 3,000 branded retail gas stations, of which more than 595 are company-operated under its own Tesoro brandname, as well as Shell, ExxonMobil, ARCO, and USA Gasoline brands.

Andeavor, formerly Tesoro, was founded in 1968 by Dr. Robert V. West Jr, and is primarily engaged in petroleum exploration and production. Tesoro is the word for treasure (or treasury) in Italian/Spanish. In 1969, Tesoro began operating its first refinery, near Kenai, Alaska: Tesoro Corp. became the first Fortune 500 company to be headquartered in San Antonio.

In the late 1990s, Tesoro grew through a series of acquisitions and initiatives that created Tesoro Corporation, the company focusing on a single core business: petroleum refining and marketing. Acquisitions expanded refining capacity from 72,000 barrels per day (11,400 m/d) to approximately 664,000 barrels per day (105,600 m/d).

Since 2010, through strategic growth, financial discipline, strong execution and the commitment of its employees, Andeavor has become one of the leading independent refining, marketing and logistics companies in the United States.

Milestones in the company's history are:

Tesoro Corporation's executive management team comprises:

Having taken over BP installations, researchers at the Political Economy Research Institute identified Tesoro as being the 24th-largest corporate producer of air pollution in the United States, releasing roughly 3,740,000 lb (1,700 t) of toxic chemicals annually. Major pollutants emitted annually by the corporation include more than 400,000 lb (180 t) of sulfuric acid. following which the Environmental Protection Agency named Tesoro a potentially responsible party for at least four superfund toxic waste sites. Tesoro has settled and/or closed each of the superfund sites for which it has been named as one of many responsible parties. Tesoro was listed as a de minimis contributor to a superfund site in Abbeville, LA, and the site has since been closed by the EPA.

Tesoro has given over $1 million in support of California Proposition 23, which aims to suspend the Global Warming Solutions Act of 2006.

Defenders of the Amazon forest in South America cite Tesoro for sourcing some of their crude oil from the Amazon. Three of Tesoro's refineries- Anacortes (WA), LA (CA) and Golden Eagle (CA), are known to process Amazonian crude oil.

On April 2, 2010, there was an explosion at the Anacortes refinery with seven deaths.

After the overthrow of Colonel Gaddafi, Tesoro bought Libyan crude oil in early April 2011 from the Vitol Group to supply its then-Hawaiian refinery.

See also: List of museums in Central Texas