Theranos Inc. () was an American privately held corporation that was touted as a breakthrough health technology company. Founded in 2003 by then 19-year-old Elizabeth Holmes, Theranos raised more than US$700 million from venture capitalists and private investors, resulting in a $10 billion valuation at its peak in 2013 and 2014. The company claimed that it had devised blood tests that required very small amounts of blood and that could be performed rapidly and accurately, all using compact automated devices that the company had developed. These claims were proven to be false.

A turning point came in 2015, when medical research professor John Ioannidis, and later professor of clinical biochemistry Eleftherios Diamandis, along with investigative journalist John Carreyrou of The Wall Street Journal, questioned the validity of Theranos's technology. The company faced a string of legal and commercial challenges from medical authorities, investors, the U.S. Securities and Exchange Commission (SEC), the Centers for Medicare and Medicaid Services (CMS), state attorneys general, former business partners, patients, and others. By June 2016, Forbes estimated that Holmes's personal net worth had dropped from $4.5 billion to "nothing". After several years of struggle, lawsuits, and sanctions from CMS, what remained of the company was dissolved in September 2018.

Theranos, Holmes and former company president Sunny Balwani were charged with fraud by the SEC in 2018. Holmes and Balwani were also charged with wire fraud and conspiracy, with Holmes being found guilty on four counts in January 2022 and sentenced that November to 11 years and 3 months in prison. Balwani was convicted on all 12 counts brought against him in July 2022, and in December 2022 was sentenced to 12 years and 11 months in prison and 3 years of probation.