Ollivander (really minor I know, saddened he never really made another appearance)
Nearly Headless Nick - whats not to love?
The Patil sisters - twins are always cool, and these two have cool names.
Fleur - Not sure why.
The Aurors - Tonks and Kingsley Shacklebolt
Aragog - I like spiders
Buckbeak - I also like Hippogriffs, and he took a swipe at Draco, what's not to love.
Dobby!
Lee + Weasly family (except Percy)
The OWL examiners (wish my exams were like that and staffed by such people)
Gilderoy Lockhart - Reminds me of a student lecturer I have, really quite vain and no idea about what he's teaching.
Odd list yes, but they are my favorites of what I consider "minor", (though Tonks, Dobby, the Weasly family are getting towards more major)
Honorable mention to... The whomping willow. I wish I had one in my garden. And maybe that pompous Ernie guy from Hufflepuff, not in my garden though, as an honorable mention I mean.