For a Thief, laws are made to be broken. Why fight a guard to claim his treasure when you can sneak by while he's dozing? No one likes this dishonorable bunch, that is, until they need one of them.
The Thief is most likely to learn Scouting, and fairly likely to learn Combat and Chaos magic. The Thief can not learn Nobility, Life Magic or Order Magic when leveling up unless some basic training in those skills is already known.
Thieves and solo heroes with the Scouting skill can prove especially useful on larger maps. Using Stealth, a careful Thief can gather masses of artifacts and resources for the Player and, especially on extra-large maps, can become a very powerful hero in itself. In fact, unless the map-maker has constucted the map with due care, a stealthed hero can explore much territory and grab treasure piles before being able to defeat the guardians of these areas and objects.
A thief with Nature Magic / Summoning (a bard) can become very powerful and is a fun hero to play. This hero can gain experience by sneaking past a stack and then turn around and attack the stack for more experience. A GM Thief with GM Summoning can sneak past dragons and then attack them with summoned mantises, phoenixes, etc.
On large maps with lots of low-level creatures, the thief class is particularly popular as the low-level creatures represent a nearly endless source of experience. Keep in mind that multiple thieves can sneak past a creature stack once each, as long as the stack itself isn't killed.
|Heroes of Might and Magic IV classes|
|Standard hero classes||Knight - Death Knight - Lord - Thief - Archer - Barbarian - Priest - Necromancer - Mage - Sorcerer - Druid|
|Advanced classes||Archmage - Assassin - Bard - Battle mage - Beast lord - Beastmaster - Cardinal - Crusader - Dark Lord - Dark Priest - Demonologist - Enchanter - Field marshal - Fire diviner - Fireguard - General - Guildmaster - Heretic - Illusionist - Lich - Lord commander - Monk - Ninja - Paladin - Prophet - Pyromancer - Ranger - Reaver - Seer - Shadow Mage - Summoner - Warden - Warlock - Warlord - Witch king - Wizard - Wizard King|