Avatars are a type of Cosmetic that you can get in Crates or buy. You can equip the ones you have (or view the ones you don't) from the "Avatar" option in the Player Menu.
Avatars appear as the Player proxy "face" in the game, and function as a visual "treat" and for Players to stylize their gameplay.
Collection[]
You can get Avatars from any free Crate and Battle Pass rewards (related to the focused Faction at the time), or buy them from the Daily Shop (the cost in Gems is equal to the rarity the Avatar have).
All new Players start with the "Aximand" Avatar equipped, and can gain the "Camba-Diaz" Avatar immediately through the starter Battle Pass (these two Avatars are always certain).
You can buy them from the Web Shop (when available) or from Offer Crates (if it comes with one), with real money.
Avatar List[]
—You can click in any, in the selection screen, to see a small bit of Lore about the selected character.
Notes[]
As you can see, there are "jumps" from some numbers to the next ones (and missing from the list). These Avatars don't appear "normally" as they are "Premium Avatars", only earned by buying them from the Web Shop, and (some) from Offer Crates.
Thus, only certain Players will be able to see and equip them (and the reason why they don't appear on the list).
Other Avatars are of the "Unimplemented Content" category [see more], and can't be viewed by anyone.