Wizard101 gives several pets from quests, but class pets in particular are those you can receive when you reach a certain level and have finished a number of quests. The first batch were the level 48 class pets that were introduced with the Advanced Pets system.
Then we have the Level 58 pets out of Wintertusk and also the Level 78 pets from your class professor. The whole lot of them dubbed "Class Pets."
Although the class pets by themselves made for some fun class pride feelings . . . they were (at least when the level 48 pets came out) really fun to play with. I remember fondly the times when players were combining pets together striving to find new and rare hybrid pets. But THAT's a topic for another day. :)
. . . and because I can get a class pet that matches my Friendly Necromancer style . . . it's awesome!