The Avatar represents the player in the game and is always surrounded by a Frame.
Players can change their Avatar by clicking on their current Avatar in the top left corner of the main screen and then clicking on "Change avatar" (the 2nd link from the top).
Avatars are unlocked by completing the Campaign, promoting Heroes, Titans or Pets, buying and upgrading Skins, or available during Special Events through quests or bundles, or via Hero Wars YouTube channel. [1]
Some Avatars, however, can not be obtained by the players and are only used for NPCs like the Guild Raid minions, Adventure and Outland bosses, as well as Boxy and Wendy.
The image on the right showcases most Avatars as of April 2021 (with no guarantee of completeness). They are resized to 80x80 pixels and joined together. Full Avatar versions (160x160 pixels) are available in the Hero Wars Fan Kit.