L5EP
L5EP was first proposed by Mike Bennett in December, 2005
Mike Bennet developed the algorithms and placed them on a site in January, 2006
https://web.archive.org/web/20090807121113/http:/geocities.com/cubiks_ruber/msm6.html
The above two messages were sent to the SpeedSolvingRubiksCube Yahoo group.
In mid-2006 James Straughan had the same idea and developed the algorithms for the MI1 method
In 2008 Kennth Gustavsson developed a naming system for each case
James Straughan developed an updated image for Kenneth's naming system
https://i140.photobucket.com/albums/r25/Athefre/L5EFinal.png
https://www.speedsolving.com/threads/last-edges-roux-amoung-other-methods.6754/post-100400
The above image and the wiki page were the cause for L5EP gaining some popularity, eventually making it's way into various methods. ZZ-Portico was an early one. Hawaiian Kociemba, Mehta, and others later followed.
The currently used naming system was developed by Andrew Mahovich and Cubingcubecuber
https://docs.google.com/document/d/1kb4JFX2WY5mh0gchb9gkbI-RoINaFfX5w0i4VJ1z5ek/edit
Source for the authors of the above L5EP algorithm sheet: