John Roos is a former United States Ambassador to Japan and a former technology lawyer. Before accepting the ambassadorship from President Barack Obama, Roos was the CEO of Silicon Valley-based law firm Wilson Sonsini Goodrich & Rosati.

Roos served as the U.S. Ambassador to Japan from 2009 to 2013, a historic period in U.S.-Japan relations where he played a key role in managing the relationship through major transitions of government. Roos led the American mission to support Japan's response to the devastating 9.0 earthquake, tsunami, and nuclear crisis on March 11, 2011. In October 2011, citing his tireless and effective leadership after March 11, the Department of State awarded Roos the prestigious Sue E. Cobb 2011 Award for Exemplary Diplomatic Service.

Prior to his ambassadorship, Roos served as Chief Executive Officer and Senior Partner at Wilson Sonsini Goodrich & Rosati, the leading law firm in the U.S. in the representation of technology, life sciences, and emerging growth companies. There he helped lead his firm during the waves of innovation in Silicon Valley, from the growth of software and communications, to the Internet Age, to the emergence of biotechnology, clean technology and renewable energy, to the social media revolution.

Roos grew up in San Francisco and attended Stanford University, where he graduated Phi Beta Kappa with Honors and Distinction, and Stanford Law School, earning his Juris Doctor in 1980, achieving Order of the Coif. Throughout his career, Roos has been active in public service, serving on a public school board in California from 1991 to 1999. Prior to becoming Ambassador to Japan, Roos served on the Stanford School of Education Dean's Advisory Board and on the Law School Dean's Advisory Council. He was elected to membership in the Stanford Associates for his long-standing volunteer service to the University.