W. Timothy Gallwey (born 1938 in San Francisco) is an author who has written a series of books in which he has set forth a new methodology for coaching and for the development of personal and professional excellence in a variety of fields that he calls "the Inner Game". Since he began writing in the 1970s, his books include The Inner Game of Tennis, The Inner Game of Golf, The Inner Game of Music (with Barry Green), Inner Skiing and The Inner Game of Work. Gallwey's seminal work is The Inner Game of Tennis, with more than one million copies in print. Besides sports, his training methods have been applied to the fields of business, health, and education.
In 1960, Gallwey was captain of the Harvard University Tennis Team. In the 1970s he learned the meditation techniques of the Divine Light Mission's Guru Maharaj Ji, which Gallwey said enhanced his powers of concentration in a manner that improved his game. In a 1973 New York Times article he described his discovery of Maharaj Ji and his decision to live in an ashram and practice celibacy. In 1997, Gallwey dedicated his book, The Inner Game of Tennis, to him.
The "inner game" is based upon certain principles in which an individual uses non-judgmental observations of critical variables, with the purpose of being accurate about these observations. If the observations are accurate, the person's body will adjust and correct automatically to achieve best performance. Gallwey was one of the first to demonstrate a comprehensive method of coaching that could be applied to many situations, and found himself lecturing more often to business leaders in the U.S. than to sports people.
Tim Gallwey's work went on to found the current movement in business coaching, life coaching and executive coaching. One of the most well known exponents of business coaching is Sir John Whitmore, who popularised Graham Alexander's and Alan Fine's GROW model of the coaching process.
In every human endeavor there are two arenas of engagement: the outer and the inner. The outer game is played on an external arena to overcome external obstacles to reach an external goal. The inner game takes place within the mind of the player and is played against such obstacles as fear, self-doubt, lapses in focus, and limiting concepts or assumptions. The inner game is played to overcome the self-imposed obstacles that prevent an individual or team from accessing their full potential. 
- Gallwey, W. Timothy (1974). The Inner Game of Tennis (1st ed.). New York: Random House. ISBN 0-394-49154-8.
- Gallwey, W. Timothy. (1976). Inner tennis : playing the game. New York: Random House. ISBN 0-394-40043-7.
- Gallwey, W. Timothy; Kriegel, Robert J. (1977). Inner skiing (1st ed.). New York: Random House. ISBN 0-394-42048-9.
- Gallwey, W. Timothy (1981). The Inner Game of Golf (1st ed.). New York: Random House. ISBN 0-394-50534-4.
- Gallwey, W. Timothy (1985). Inner Game of Winning. Listen USA. ISBN 0-88684-064-3.
- Green, Barry; Gallwey, W. Timothy (1986). The inner game of music (1st ed.). New York: Anchor Press/Doubleday. ISBN 0-385-23126-1.
- Gallwey, W. Timothy. (2000). The Inner Game of Work. New York: Random House. ISBN 0-375-50007-3.
- Gallwey, W. Timothy. (2009). The Inner Game of Stress: Outsmart Life's Challenges, Fulfill Your Potential, Enjoy Yourself. New York: Random House. ISBN 1-4000-6791-X.
- du Plessix Gray, Francine, Blissing Out in Houston, New York Review of Books, December 13, 1973
- Morgan, Ted, Oz in the Astrodome, New York Times, December 9, 1973, p.96
- Anderson, Walter Truett. The Upstart Spring: Esalen and the Human Potential Movement iUniverse 2004, ISBN 0-595-30735-3 p. 259
- Gallwey, W. Timothy (2000). The inner game of work. New York: Random House. p. 27. ISBN 0-375-50007-3.
- Whitmore, John K. (2002). Coaching for Performance: Growing People, Performance and Purpose. London: Nicholas Brealey Publishing. p. 10. ISBN 1-85788-303-9.