The Noun Project - Creating, Sharing and Celebrating the World's Visual Language
Discipline. - a macOS Big Sur icon pack with 100+ icons
Nucleo - Commercial vector icons and accompanying apps to manage and customize them.
macOS Big Sur icons - Original icons in PNG ready for download
Font Awesome - Font Awesome makes it easy to add vector icons and social logos to your website. And version 5 is redesigned and built from the ground up!
Icons8 Apps - 1M+ professional icons, illustrations, and photos for web, Mac, Windows, and Linux