There are seven classes of hero in Age of Magiс with each faction aiming to have at least one of each.
Tank — Tough heroes who are easily recognizable by their enormous health-pools, defensive capabilities, and the abilities to taunt enemies and self-heal.
Melee Damager — Powerful close combat heroes. Possesses the ability to engage in quick and effective attacks on their enemies. Many melee damager characters often have abilities that break the enemies defences or leaves them with a DoT.
Ranged Damager — From the back of the pack these heroes use precision and power to eliminate foes. These characters have moderate healthpools and work well with other characters that can protect them in battle.
Rogue — Nimble heroes who use an assortment or abilities to increase evasion and taunt enemies to either attack other characters or the rogue like heroes themselves.
Caster — A sorcerous hero that uses magic to inflict damage to the enemy and apply various effects on their own or enemy heroes. Many of these characters possess powerful AoE abilities and even stronger single target attacks. Like Ranged units, these characters work well with characters who can protect them like tanks and even some rogues.
Healer — The support and centre of most teams, these heroes assure your characters can last in battle to perform their devastating combinations. Each healer is unique in the way they work and you can find one that will most definitely work with your playstyle.  
Boss — Unique heroes with immensely strong abilities. Many of these characters offer powerful passive abilities to units of the same faction.