Toon Link did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
Toon Link (also known as Cel-Shaded Link or simply Link) is the name often accredited to the Link that appears primarily in the Adult Timeline of the Zelda Timeline. The "Toon Link" that is often named as such is based on the two that appear in The Wind Waker, Phantom Hourglass, and Spirit Tracks. Outside the Zelda series spin-off of Hyrule Warriors, Toon Link appears in a number of Super Smash Bros. starting with Brawl.
There have been five canonical Toon Links:
One that appeared in both The Wind Waker and Phantom Hourglass.
It is shown that this Toon Link appears in most spin-off titles where he is known as "Toon Link".
One that appeared in Spirit Tracks.
One that appeared in Four Swords and Four Swords Adventures; where he was split into four parts.
One that appeared in The Minish Cap.
One that appeared in Tri Force Heroes.
Though this Link is the same as the one that appears in A Link Between Worlds, that game uses a more realistic art-style, thus not technically a 'Toon' Link.