There are currently 44 Heroes available to play. The newest edition being Skale, the Stone Guardian.
Heroes are any of the playable characters within Heroes of Order and Chaos. Each Hero is unique in their stats, skills, itemization, and play style.
They are grouped into four classes based on their comparative use. These classes are:
Guardian FighterMage Support
Teams are generally composed of selections from each category in an effort to incorporate the various strengths of each class. Within each Class, heroes are subdivided into roles that denote their current meta-game such as Carry, Bruiser, Tank, Nuke, and Support.
You can also buy Skins for your hero to change their look. Skins are only obtainable using runes or via the lottery.