John L. Hennessy

John Leroy Hennessy (born September 22, 1952) is an American computer scientist and businessman who has served as the chairman of Alphabet Inc. since 2018. One of the founders of MIPS Technologies and Atheros, he was the 10th president of Stanford University from 2000 to 2016. He was succeeded as president by Marc Tessier-Lavigne. Marc Andreessen called him "the godfather of Silicon Valley."

Along with David Patterson, Hennessy was a recipient of the 2017 Turing Award for their work in developing the reduced instruction set computer (RISC) architecture, which is now used in 99% of new computer chips.

Hennessy was raised in Huntington, New York, as one of six children. His father was an aerospace engineer, and his mother was a teacher before raising her children. He is of Irish-Catholic descent, with some of his ancestors arriving in America during the potato famine in the 19th century.

He earned his bachelor's degree in electrical engineering from Villanova University, and his master's degree and Doctor of Philosophy in computer science from Stony Brook University.

Hennessy became a Stanford faculty member in 1977. In 1981, he began the MIPS project to investigate RISC processors, following preliminary investigations at Berkeley by David A. Patterson. On 1984, he used his sabbatical year to found MIPS Computer Systems Inc. to commercialize the technology developed by his research. Returning to Stanford, he became the Willard and Inez Kerr Bell Endowed Professor of Electrical Engineering and Computer Science in 1987. In 1988, Hennessy and Patterson began a three-year effort to write the first edition Computer Architecture: A Quantitative Approach, which described RISC instruction sets and cost-performance tradeoffs.

As a full Stanford professor, Hennessy took administrative roles of growing breadth. He was director of Stanford's Computer System Laboratory (1989–93), a research center run by Stanford's Electrical Engineering and Computer Science departments. He was chair of the Department of Computer Science (1994–96) and Dean of the School of Engineering (1996–99). In 1999, Stanford President Gerhard Casper appointed Hennessy to succeed Condoleezza Rice as Provost of Stanford University. When Casper stepped down to focus on teaching in 2000, the Stanford Board of Trustees named Hennessy to succeed Casper as president. In 2008, Hennessy's compensation exceeded $1 million, the 23rd highest among all American university presidents.

Hennessy has been a board member of Google (later Alphabet Inc.), Cisco Systems, Atheros Communications, and the Gordon and Betty Moore Foundation. He was elected to the American Philosophical Society in 2008.

On October 14, 2010, Hennessy was presented a khata by the 14th Dalai Lama before the latter addressed Maples Pavilion.

In December 2010, Hennessy coauthored an editorial with Harvard University President Drew Gilpin Faust urging the passage of the DREAM Act; the legislation did not pass the 111th United States Congress.

Hennessy is married to Andrea Berti, whom he met in high school.