No. 48: James Spilker Jr. and Anna Marie Spilker

Amount donated in 2012: $28-million

Beneficiary: Stanford School of Engineering

Background: Mr. Spilker, who helped develop the Global Positioning System, known as GPS, is a co-founder of AOSense, a company that designs and builds scientific sensors. He is also a co-founder of Stanford Telecommunications, which he sold in 1999. Anna Marie Spilker founded New Pacific Investments, a real-estate investment company.

The Spilkers pledged $28-million to the Stanford School of Engineering to endow a professorship and provide other support. The university has named an engineering and applied-sciences building for the couple. Since 2001, Mr. Spilker has served as a professor of electrical engineering and aeronautical and astronautical engineering at the university. He earned bachelor’s and master’s degrees and a Ph.D. at the university in 1955, 1956, and 1958.