Richard M. Stallman, aka RMS, creator of the concept of free software, president of the Free Software Foundation, and the primary author of the vital free software/open-source license the Gnu Public License (GPL), became ill during a speech at the Polytechnic University of Catalonia in Barcelona, Spain and had to taken to a hospital.
Some reports on Twitter said that Stallman had suffered a heart attack, but that was not the case. He began suffering in the middle of his speech and para-medics were called in Stallman tried to continue his speech, but finally had to give it up. He kept his sense of humor throughout the episode. When he ambulance crew took over 20 minutes to arrive, Stallman made a joke of it saying that due to Spain's recent austerity cuts "Here's the truth, [Spain's President Mariano] Rajoy wants to kill us all." (Spanish language link).
It appears that Stallman was suffering from high blood pressure or hypertension. Officially, according to the FSF, Stallman, who was first treated at the site, was taken to a hospital and later discharged.
Stallman is a father figure of the modern free software movement. While, personally, he objects to the term open-source software, his work is also regarded as one of its ancestors. Stallman also claims that he's one of the creators of Linux. Supporters of this position call Linux, GNU/Linux.
Over the last few years, Stallman, despite his continuing popularity is free software circles, has become seen as something of a crank. For example, after Steve Jobs' death, Stallman wrote that while “I’m not glad he’s dead, but I’m glad he’s gone.”
Be that as it may, Stallman was the primary creator of the GPL and GNU C and many other important free software development tools under the GNU name. Without his programming and licensing work, the modern Linux and free/libre/open source software (FLOSS) world wouldn't exist. Health permitting, he will continue to fight for his vision of free software.