You can learn a lot from Wikipedia's NHL mascot page

Clearly, the decline of Encyclopedia Britannica is due to the fact that they didn't have comprehensive entries on topics such as this one: List of NHL mascots.

I thought I knew a lot about NHL mascots, but after reading this page I also learned that:

• Dallas, Edmonton, New York and Philadelphia* have never had mascots.
• The giant purple octopus the Red Wings use in the playoffs is called Al.
• Bailey, from the L.A. Kings, wears number 72 -- as in 72 degrees F, a nice sunny day in L.A.
  
• The Colorado Avalanche have had two mascots in their relatively short history. A St. Bernard and a Yeti.
• Harvey the Hound (Calgary) was the NHL's first mascot*, introduced in 1983.
• In Phoenix, Howler wears #96 on his jersey, they year the Jets moved to Phoenix. (Take that, Winnipeg.)
• The Ducks mascot, Wildwing, has a last name: Flashblade.
• The former Quebec Nordiques mascot was Badaboum, who looks a bit like a walrus.
• The former Winnipeg Jets mascot was Bennie, who looks like what happens when the Philly Phanatic mates with Grimace.

"The Flyers debuted a short-lived skating mascot named Slapshot in 1976. It remains the only mascot in Flyers' team history."