See the full Mercenary List for all mercenaries in Atlantica Online.
If you follow the link to any merc's page, it will tell you how that merc can be recruited.
Tip: Some mercenaries are event mercenaries and while you can occasionally obtain them, you may not be able to get skills for them, or the skills may be obtainable, but prohibitively expensive; which makes them far less useful than another merc that you can fully skill up. Check the market and with other guild and nation members whether skills are available for any given merc before you recruit that merc.
The portraits at the bottom toward the right side of the screen shows a portrait for each Character currently in your Formation. Press 1 - 9 to select another character in your formation (1 is always your main character). See the Character page for more info about characters and character portraits.
Some of these mercenaries belong to the Diabolic, Shadow or Shaolin Legions. Some can be can be obtained by completing mercenary recruitment quest chains, some can be won from events. Most can be bought from the market.
Legion Mercenaries are named Trainee XYZ, because there are, in many cases, also NPCs with the same name as the Mercenary. This makes it easy to tell the difference. Trainee XYZ is the mercenary and XYZ is the NPC.
Guard Mercenaries are place holder mercenaries that are automatically added to new characters' formations. They can only level up to level 60, allowing new characters time to recruit permanent mercenaries to replace them.
Mercenaries are assigned grades to give players a rough idea of how good a particular merc is. Grade A is the highest (best) grade and D is the lowest. Often the grade also reflects the cost associated with owning and leveling up a particular merc. Grade A mercenaries have the highest crystal/jewel upgrade cost and often the most expensive skills.
Don't rely only on a mercenary's grade for determining the quality of a merc. A lot more matters, including how well that merc fits into your formation. Particularly for PvE, you don't need a team of only Grade A mercs to be able to reach maximum level.
Grade D Mercs
Some of these mercenaries can be found wandering around in towns or on roads. You can recruit Grade D mercs Archer, Gunner, Shaman, Spearman and Swordsman after level 5 from NPCs Jang Gil San, Ou Yang Feng, Shuichi or Im Guk-jung for 5,000 gold each.
The list below categorizes Mercenaries by Magic, Melee or Ranged. You can, of course, classify mercenaries in many other ways. We have done so in a few places on the AO Wikia. For example, see pages discussing Healers, Resurrecting and Stun.
Each Mercenary, like each Main Character, can have multiple Magic Skills. See the page for each mercenary to see what skills he or she can use. Also see the Skills page for a discussion of skills and links to Skill lists.
The Main Character cannot be removed from the Formation, occupying one spot at all times. A formation can consist of any combination of Grade D Mercenaries. Mercenaries of Grade C, B, or A are limited to one each. Exceptions to this are Dual Beast Trainer, Lady Knight, Oracles, Janissary, Hwarang, Canoneer, Minstrels and Punisher. The Sealed Orbs used to hire these mercenaries show these limits.
The maximum number of mercenaries that a player can hire is dependent on a combination of the player's hero level and available Mercenary Storage.
Players can also fire unwanted mercenary to make room for new or better fitting merc in their formation. Be aware that by firing, you lose this mercenary and any investment you have in that mercenary (e.g. growth vials, experience gained, skills learned). If possible, you may be better off storing or employing the merc instead, if possible, to retain your investment.