Get an avatar based on the first letter of given name. Image files can be named a.png, b.png, c.png etc. and placed in your theme folder. Works with Wordpress, Budypress and BBpress.
copy paste the code from "functions.php" in your theme's "functions.php" or in "bp-custom.php" (/wp-content/plugins/bp-custom.php). Add the Avatar folder to ../images/ in your theme directory. These sample images are from https://www.flaticon.com/packs/profession-avatars (License: Flaticon Basic License).