Robohash - Generate unique images from any text.
Evatar - The most straightforward global avatar service.
DiceBear Avatars - Pixel-Art Avatar Generator and -Provider by Identifier/Hash/Seed in JavaScript for Browsers and...
Identicon - An Identicon is a avatar which represents a hash of unique information
Gravatar - Gravatar (an abbreviation for globally recognized avatar) is a service for providing...
Libravatar - Libravatar is a service which delivers your avatar to other websites.