The game offers a big list of types of heroes to recruit. Rangers are explorers and will travel the map, uncovering hidden areas. They're armed with a bow and are good at a distance. Thieves are also good at ferreting out hidden gold that can be added to your coffers. They will also be the first to go after bounties, which are rewards you place on locations or even the heads of enemies.
Warriors are the sturdiest of the bunch, and are the basic knight in shining armor type.
Wizards are the most powerful, but are about as hardy as hamsters and are usually the first ones killed until they really get up in level. There are more types of heroes to recruit, but these are the basic building blocks of your army. Each type of hero has a specific guild that allows you to recruit a set number of heroes. Say you build a Wizards' Guild. Each one can support up to four wizards.