Colonel Veers

I love this unit. Firstly Veers commands an AT-AT which is already awesome in itself. In addition to the AT-AT characteristics and the deploy stormtrooper ability, Veers has the Maximum Firepower ability. When activated, it spits out a steady stream of laser fire that destroys the target instantly if it is a structure. In the case where you target an individual unit, it will destroy it and anything around it instantly. I managed to kill a full health Obi Wan with this ability.

Captain Piett

The Colonel Veers of space battles. Piett commands an Imperial Star Destroyer. In addition to all the ISD characteristics and abilities, Piett has a special ability Proton Beam which either disables all of the targeted starships hardpoints or causes a hell of a lot of damage to the ship.

Mara Jade

The Emperor’s Hand from the Expanded Universe. She does not wield a lightsaber in EaW as this is around A New Hope timeline. She is good at dispatching enemy troops with her blaster and has two special abilities. The first is a thermal detonator ability to toss at enemy vehicles and structures (in the case of a vehicle make sure it does not move or you will end up tossing your detonator to the ground). The second is Force Corrupt which she borrows from her master Palpatine, to turn any infantry around her to her side.

Boba Fett

The most notorious and feared bounty hunter in the galaxy. This unit is great in the sense that it operates both in space and on the ground. In space, he can handle hoards of enemy fighters and bombers with his lasers; and with his seismic charge ability he can help in destryoing capital ships and stations. On the ground, Fett is more than capable in killing enemy infantry with his blaster. If infantry surround him, he can just burn his way around them by using his flame thrower in a 180 degree arc in front of him. He can also use his jetpack to fly to any point on the map without having to go around any obstacles. Fantastic unit.

Darth Vader

Vader is about as powerful ground unit as you are going to find in EaW, as he is capable of annihilating enemy armies single-handedly. He can shrug off any blaster fire or vehicle laser fire. His lightsaber can slash through infantry like a knife through butter and given time can destroy armoured units as well. His two special abilities are Force Crush and Force Push. Force Crush can destroy any enemy vehicle in a matter of seconds while Force Push can hurl and instantly kill any foolish infantry units who come close to him. To kill him you will have to surround him with armoured units and an anti-infantry turret, bombard him with artillery fire or conduct Y-Wing runs on him.

In space, he fights in his TIE Advance X1 with a squad of TIE Fighters and is effective at destroying enemy fighters and bombers quickly. When his squad health starts to diminish (he is always the last man in the squad to die), then you can just use his special ability to call in new wingmen and bring the whole squad health back to full.

Emperor Palpatine

Need I say more? By the time of the original trilogy, he looks like an old man with a cane but he is much more than that in EaW. Like Mon Mothma he reduces the cost of any units on the planet in which he stays on by 25%. When entering a battle, he is near invulnerable on the ground. He takes more damage than Vader does and is capable of nursing himself constantly back to full health as he steals life from nearby enemies. His lightsaber will slash through enemy infantry and can destroy vehicles given time. In addition, he gets Force Lightning which kills any enemy infantry within a 180 degree arc in front of him. He also has Force Corrupt which will convert enemy infantry to his side. He is the most powerful hero in the game.