Walter Boughton Pitkin (born February 6, 1878 in Ypsilanti, Michigan; died January 25, 1953 in Palo Alto, California) was an American lecturer in philosophy and psychology at Columbia University (1905-09), and professor in the Columbia University School of Journalism (1912-43). He has written some self help books like Life Begins at 40 (New York, Whittlesey house, McGraw-Hill, 1932) and The Psychology of Happiness. His A Short Introduction to the History of Human Stupidity was translated into fifteen languages. Pitkin was a member of the New Realism school in philosophy, writing on its relation to biology.

Pitkin was father (by Mary Gray Pitkin) to five sons: Richard G., John G., David B., Robert B., and Walter B Pitkin Jr. He later married Katherine B. Johnson.

David Howell Evans (born 8 August 1961), more widely known by his stage name The Edge (or just Edge), is a musician best known as the guitarist, backing vocalist, and keyboardist of the Irish rock band U2. A member of the group since its inception, he has recorded 12 studio albums with the band and has released one solo record. As a guitarist, The Edge has crafted a minimalistic and textural style of playing. His use of a rhythmic delay effect yields a distinctive ambient, chiming sound that has become a signature of U2's music.

The Edge was born in England to a Welsh family, but was raised in Ireland after moving there as an infant. In 1976, at Mount Temple Comprehensive School, he formed U2 with his fellow students and his older brother Dik. Inspired by the ethos of punk rock and its basic arrangements, the group began to write its own material. They eventually became one of the most popular acts in popular music, with successful albums such as 1987's The Joshua Tree and 1991's Achtung Baby. Over the years, The Edge has experimented with various guitar effects and introduced influences from several genres of music into his own style, including American roots music, industrial music, and alternative rock. With U2, The Edge has also played keyboards, co-produced their 1993 record Zooropa, and occasionally contributed lyrics. The Edge met his second and current wife, Morleigh Steinberg, through her collaborations with the band.