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While Courage Wolf often encourages people to overcome life's obstacles, Insanity wolf tells his viewers to rape, kill, and commit other acts of insanity.
There is even a Facebook app for Insanity Wolf.
Although the Insanity Wolf meme began in 2009, the wolf image from which this meme is derived has been appearing online since at least 2006.
The image has also been used in a 1999 printing of Sir Arthur Conan Doyle's The Hound of the Baskervilles.
A TinEye Image Search shows that this fierce wolf has been used as a popular forum avatar for a number of years. Given the immense presence of this photo and the different ways it has been used, it is likely that it is a commonly available piece of stock photography.