'Tis the season to bump the thread.
rudolph was a marketing ploy by montgomery ward
True, but that makes him no less canonical. After all, every part of the Santa Claus legend was invented by someone at some time. As long as a majority of the public accept Rudolph as part of the main line-up, he's canon.
The inside of the back cover of my copy of the original book by Robert L. May (I'm a kid at heart) tells how Montgomery Ward asked him to write a Christmas story to give away to customers, and how it became a runaway hit. It's interesting, to me at least.
I recall a Far Side cartoon in which Santa is writing a cookbook with the title "Nine Ways to Serve Venison." It doesn't say "Eight Ways," so apparently Gary Larson thought of Rudolph as official. I have also seen Christmas cards lately referring to nine reindeer as though that is now the accepted number.
Having said all that, according to the original story, Rudolph was NOT made a permanent part of Santa's reindeer team. He was recruited to help guide the sleigh on one foggy night, and Santa promised Rudolph would guide the sleigh on future Christmases
only when it was foggy. So according to the original Rudolph canon, there are usually only eight reindeer, with a ninth on standby.
I don't care. There nine as far as I'm concerned.