Richard Stallman, the founder of the Free Software Movement- and of the Free Software Foundation (FSF).
Richard Matthew Stallman (frequently abbreviated to RMS) (born March 16, 1953) is the founder of the free software movement, the GNU Project, and the Free Software Foundation. An acclaimed hacker, his major accomplishments include Emacs (and the later GNU Emacs), the GNU C Compiler, and the GNU Debugger. He is also the author of the GNU General Public License (GNU GPL or GPL), the most widely-used free software license, which pioneered the concept of the copyleft.
Since the mid-1990s, Stallman has spent most of his time as a political campaigner, advocating free software and campaigning against software idea patents and expansions of copyright law. The time that he still devotes to programming is spent on GNU Emacs. He supports himself by being paid for around half of the speeches he gives.
Stallman was born in Manhattan, New York, to Alice Lippman. His first access to a computer came during his senior year at high school in 1969. Hired by the IBM New York Scientific Center, Stallman spent the summer after his high-school graduation writing his first program, a preprocessor for the PL/I programming language on the IBM 360. "I first wrote it in PL/I, then started over in assembly language when the PL/I program was too big to fit in the computer," he later said.
Stallman was simultaneously a volunteer Laboratory Assistant in the biology department at Rockefeller University. Although he was already moving toward a career in mathematics or physics, his analytical mind impressed the lab director such that a few years after Stallman departed for college, his mother received a phone call. "It was the professor at Rockefeller," she recalled. "He wanted to know how Richard was doing. He was surprised to learn that he was working in computers. He'd always thought Richard had a great future ahead of him as a biologist." 
In June 1971, as a freshman at Harvard University, Stallman became a programmer at the MIT AI Laboratory, where he became a fixture in the hacker community. During these years, he was perhaps better known by his initials, "RMS." In the first edition of the Hacker's Dictionary, he wrote, "'Richard Stallman' is just my mundane name; you can call me 'rms'."  Stallman graduated from Harvard with a BA in Physics in 1974. He then enrolled at MIT as a graduate student, but abandoned his pursuit of graduate degrees while remaining a programmer at the MIT AI Laboratory.
In the 1970s, Stallman was a legendary hacker at MIT's AI Lab. He left in 1984 to found the FSF, and to start the GNU project. He is also the author of the GNU General Public Licence (GPL), the licence most widely used by open source software programmers, and the model on which Creative Commons licences are based.
Excerpts from a detailed biography at Answers.com
Decline of MIT's hacker culture
In the 1980s, the hacker community in which Stallman lived began to dissolve. The emergence of "portable software" — software that could be made to run on different types of computers — meant that the ability for computer users to modify and share the software that came with computers was now a problem for the business models of the computer manufacturers. To prevent their software from being used on their competitors' computers, manufacturers stopped distributing source code and began restricting copying and redistribution of their software by copyrighting it. Such restricted software had existed before, but now there was no escape from it.
In 1980 Richard Greenblatt, a fellow AI lab hacker, founded Lisp Machines Incorporated to market Lisp machines, which he and Tom Knight designed at the lab. Greenblatt rejected outside investment, believing that the proceeds from the construction and sale of a few machines could be profitably reinvested in the growth of the company. In contrast, Russ Noftsker and other hackers felt that the venture-capital funded approach was better. As no agreement could be reached, most of the remaining lab hackers founded Symbolics. Symbolics recruited most of the remaining hackers — most notably Bill Gosper — and they left the AI lab. Symbolics forced Greenblatt to resign too by quoting MIT policies. While both companies delivered proprietary software, Stallman believed that LMI, unlike Symbolics, had tried to avoid hurting the lab.
For two years, from 1982 to the end of 1983, Stallman singlehandedly duplicated the efforts of the Symbolics programmers, in order to prevent them from gaining a monopoly on the lab's computers. While Stallman did not participate in the counterculture of the 60s, he found inspiring its rejection of wealth as the main goal of life, and this may have played a role in his actions at this time. However, he was the last of his generation of hackers at the lab. He rejected a future where he would have to sign non-disclosure agreements and perform other actions he considered betrayals of his principles, and chose instead to share his work with others in what he regarded as a classical spirit of scientific collaboration.
Stallman argues that software users should have freedom — in particular, the freedom to "share with their neighbor" and to be able to study and make changes to the software that they use. He has repeatedly said that attempts by proprietary software vendors to prohibit these acts are "antisocial" and "unethical". The phrase "software wants to be free" is often incorrectly attributed to him, but Stallman argues that this is a mis-statement of his philosophy. He argues that freedom is vital for the sake of users and society and not merely because it may lead to improved software. Consequently, in January 1984, he quit his job at MIT to work full time on the GNU project, which he had announced in September 1983. He did not complete a Ph.D. but has been awarded four honorary doctoral degrees (see below).
In 1985, Stallman published the GNU Manifesto, which outlined his motivation for creating a free operating system called GNU, which would be compatible with Unix. The name GNU is a recursive acronym for GNU's Not Unix. Soon after, he incorporated the non-profit Free Software Foundation (FSF) to employ free software programmers and provide a legal infrastructure for the free software community.
In 1985, Stallman invented and popularized the concept of copyleft, a legal mechanism to protect the modification and redistribution rights for free software. It was first implemented in the GNU Emacs General Public License, and in 1989 the first program-independent GNU General Public License was released. By then, much of the GNU system had been completed, with the notable exception of a kernel. Members of the GNU project began a kernel called GNU Hurd in 1990, but a risky design decision proved to be a bad gamble, and development of the Hurd was slow.
By producing software tools needed to write software, and publishing a generalised license that could be applied to any software project (the GPL), Stallman helped make it easier for others to write free software independent of the GNU project. In 1991, one such independent project produced the Linux kernel. This could be combined with the GNU system to make a complete operating system. Most people use the name Linux to refer to both the combinations of the Linux kernel itself plus the GNU system, a usage some view as unfairly minoritizing the value of the GNU project, as discussed below.
Stallman accepts terms such as libre Software, FLOSS, and "unfettered software," but prefers the term "free software" since a lot of energy has been invested in that term. (For similar reasons, he argues for the term "proprietary software" rather than "closed source software", when referring to software that is not free software.)
The term "free software", however, can mean either "unrestricted software" or "zero-cost software" or both. Over the years, people have tried to come up with a more intuitive and less ambiguous term. See gratis versus libre and open source software.
Stallman strongly objects to the term "open source" to replace the term "free" since he says it hides the goal of freedom. He declines interviews for stories that would label his work as "open source," claiming that they would misrepresent his views.
GNU/Linux naming controversy
While often closely associated with GNU/Linux, Stallman's relationship with it is occasionally controversial. Most notably he has insisted that the term "GNU/Linux" or "GNU+Linux" be used to refer to the operating system created by combining the GNU system and the Linux kernel. He claims that the connection between the GNU project's philosophy and its software is broken when people refer to the combination as merely "Linux." This practice is described as "just ridiculous" by Linus Torvalds in the documentary Revolution OS. Nevertheless, Torvalds is also quoted as saying: "Think of Richard Stallman as the great philosopher and think of me as the engineer."
Copyright, patents, and trademarks
Stallman claims that the term "Intellectual Property" is designed to confuse people, and is used to prevent intelligent discussion on these specific laws by lumping together areas of law that have little or nothing in common. Although not a lawyer, he has argued that by referring to these laws as "property" laws, the term biases the listener when thinking about how to treat these issues.
"These laws originated separately, evolved differently, cover different activities, have different rules, and raise different public policy issues. Copyright law was designed to promote authorship and art, and covers the details of a work of authorship or art. Patent law was intended to encourage publication of ideas, at the price of finite monopolies over these ideas--a price that may be worth paying in some fields and not in others. Trademark law was not intended to promote any business activity, but simply to enable buyers to know what they are buying."
Stallman has received numerous prizes and awards for his work, amongst them:
1990: MacArthur Fellowship 1991: The Association for Computing Machinery's Grace Murray Hopper Award "For pioneering work in the development of ... EMACS" 1996: Honorary doctorate from Sweden's Royal Institute of Technology 1998: Electronic Frontier Foundation's Pioneer award 1999: Yuri Rubinsky Memorial Award 2001: Second honorary doctorate, from the University of Glasgow 2001: The Takeda Techno-Entrepreneurship Award for Social/Economic Well-Being (武田研究奨励賞) 2002: National Academy of Engineering membership 2003: Third honorary doctorate, from the Vrije Universiteit Brussel 2004: Fourth honorary doctorate, from the Universidad Nacional de Salta.  2004: Honorary professorship, from the Universidad Nacional de Ingeniería del Perú.
Interview by Richard Poynder, here at http://poynder.blogspot.com/2006/03/interview-with-richard-stallman.html
Stallman, Richard M. (2002). Free Software, Free Society: Selected Essays of Richard M. Stallman. Cambridge, Massachusetts: GNU Press. ISBN 1882114981. (Also available online in various formats, e.g. PDF .)
Williams, Sam (2002). Free as in Freedom: Richard Stallman's Crusade for Free Software, O'Reilly Media. ISBN 0596002874., chapter 3. Available online, accessed on 18 February, 2005
Various (1999). Open Sources: Voices from the Open Source Revolution, O'Reilly Media. ISBN 1-56592-582-3.. Stallman chapter available online, accessed on 18 February, 2005