The Noun Project (link) is one of those rare websites that’s simple, useful and full of good stuff. I’d have written a super long post extolling how much I like this site and have used it over the last few years but I think I can condense it to a few sentences.
ALL of the icons I’ve ever needed exist on their site, they have a great ‘Pro’ licensing scheme that won’t break the bank and you’d be hard pressed to find something missing from their catalog.
Heck, quite a few of their icons have made it onto this site for various purposes.
I highly recommend heading to their site if you’re ever in need of an icon.