Tony Nicklinson, 58, passed away in his sleep Wednesday morning -- several days after he was denied the "right to die" by Britain's High Court.
Nicklinson's family confirmed his death on Twitter.
You may already know, my Dad died peacefully this morning of natural causes. he was 58.— TonyNicklinson (@TonyNicklinson) August 22, 2012
before he died, he asked us to tweet: 'Goodbye world the time has come, I had some fun'— TonyNicklinson (@TonyNicklinson) August 22, 2012
Thank you for your support over the years. We would appreciate some privacy at this difficult time. Love, Jane, Lauren and Beth— TonyNicklinson (@TonyNicklinson) August 22, 2012
The locked-in syndrome sufferer -- fully conscious, yet immobile since 2005 -- died of natural causes. He contracted pneumonia and "refused food" shortly after the court's "devastating" decision on August 16, according to The Daily Mail.
The Melksham, Wiltshire resident lost the ability to speak and move from the neck down after suffering a severe stroke.
Nicklinson -- with the support of his wife, Jane, and adult children, Lauren and Beth -- has been fighting laws prohibiting euthanasia since January. The High Court rejected his legal "right to die," disallowing doctors to kill him without legal consequences. The family was planning an appeal.
His right-to-die efforts also included an online petition on Change.org. It has been signed by more than 23,000 supporters worldwide to date.
Nicklinson gained global support online with social media. Using a sophisticated computer that tracks his eye movements, the 58-year-old paralyzed from the neck down was able to tweet for the first time on June 13, 2012.