The original Starcraft: Brood War expansion game had eleven units per race. With the exclusive info released by PCGamer (August 2007 edition), Blizzard Entertainment revealed at least 16 units should be expected per race. Below you can take a look at the different Protoss units.
Zealot - Zealots are the standard infantry unit of the Protoss.
Stalker - Stalkers are an enhanced type of dragoons operated by fallen dark templars.
Immortal - Immortals are effective against Terran tanks and heavy ranged units.
Observer - Confirmed to return in Starcraft II, but details of enhancements or new abilities are not yet revealed
Colossus - Colossus are four-legged mechanical units equipped with two beam guns that sweep through enemy units one at a time.
Phoenix - The Phoenix are anti-air flying fighters with a fearsome ability.
Phase Prism - Phase Prisms replace the Scout transporting vessel.
Warp Ray - Warp Rays are anti-air and anti-infantry units with additional damage the longer they fire a single target.
Mothership - The Mothership is at the top of the Protoss tech tree. Only one Mothership can be built at a time.
High Templar - The High Templar still creates Psionic Storms, but has gained a new ability similar to Arbiter’s Stasis Field.
Dark Templar - The stealthed melee units from the original Brood War are back.
Twilight Archon - They are the Protoss tank unit wreaking havoc through enemy defenses.
Tempest - They replace the old Carriers, equipped with an enhanced shield that activates when its attacked by ground units and defense structures.
Soul Hunter - Soul Hunters are robotic units that hover above the ground.
Reaver - The old robotic-slug Reaver unit is back. With the use of a Phase Prism, the reavers are devastating against enemy SCVs and Drones.
Phase Cannon - Phase Cannons can now phase and shift into an energy form, and move around freely to another location where it can materialize again to unleash its energy blasts.
Star Relic - The Star Relic is a dangerous unit. It can create a cloak field to make ground and air units invisible, and even structures.