Blaster:
Ranged heroes that do massive amounts of damage but have very little hit points.

Primary:
Assault Rifle
Electrical Blast
Energy Blast
Fire Blast
Ice Blast
Archery
Sonic Blast

Secondary:
Devices
Electricity Manipulation
Energy Manipulation
Fire Manipulation
Ice Manipulation

Controllers:
The masters of crowd control. Their hit points and damage are low but they can lock down enemies better than any other Hero.

Primary:
Earth Control
Fire Control
Gravity Control
Ice Control
Illusion Control
Mind Control

Secondary:
Empathy
Force Field
Kinetics
Radiation Emission
Storm Summoning
Sonic Resonance
Trick Arrow

Defenders:
Heroes specialized in the field of buffing their teammates and debuffing their enemies. Just like controllers their damage and hit points are low.

Primary:
Empathy
Force Field
Kinetics
Radiation Emission
Storm Summoning
Sonic Resonance
Trick Arrow

Secondary:
Dark Blast
Electrical Blast
Energy Blast
Psychic Blast
Radiation Blast
Sonic Blast
Archery

Scrappers:
These are your melee combat monsters. They can do lots of damage to an enemy with their attacks. Their defenses are decent but not quite as good as the tank's.

Primary:
Broadsword
Claws
Dark Melee
Katana
Martial Arts
Spines

Secondary:
Dark Armor
Invulnerability
Regeneration
Super Reflexes

Tankers:
The best defensive heroes in the game. They have the most hit points as well as the ability to take one for the team. They deal decent melee damage but no where close to the scrapper.

Primary:
Fiery Aura
Ice Armor
Invulnerability
Stone Armor

Secondary:
Battle Axe
Energy Melee
Fiery Melee
Ice Melee
Stone Melee
Super Strength
War Mace

Peacebringers:
Kheldians who have come to Earth to hunt nictus. They have bonded with humans in a voluntary relationship so that the nictus can be eliminated. Kheldians have a little bit of all the other Heroes in them. Peacebringers tend to have more of a melee/defender feel to them.

Primary:
Luminous Blast

Secondary:
Luminous Aura

Warshades:
Nictus who have changed their ways and decided to help the peacebringers eliminate the evil nictus. There is no voluntary relationship between the human and the nictus since it was put into the human through experimentation. Warshades tend to have more of a ranged/controller feel to them.

Primary:
Umbral Blast

Secondary:
Umbral Aura

Note: Peacebringers and Warshades are only playable once you've had a hero reach level 50.