Canon for the Nightmare on Elm Street series:
The films released in theatres and home video.
Nightmares on Elm Street comic book series.
Freddy Krueger's: Tales of Terror novel series.
A Nightmare on Elm Street comic book series.
A Nightmare on Elm Street novel series.
A Nightmare on Elm Street comic book series.
New Line Cinema's Tales of Horror comic book series.
Freddy vs. Jason vs. Ash comic book series.
Freddy's Nightmares - A Nightmare on Elm Street: The Series.
Note: The television series Freddy's Nightmares is loosely considered canon. Some episodes do present altered backstories/dates from that of the given films. Though most episodes do not interfere with the film events and can fit nicely in the given timeline, the backstories/dates presented in the television series should not be favored over the films.