Majoru Oakheart
Adventurer
Less a summons and more a Shaman's Spirit Companion. Unless you're calling the Shaman a controller because they have a "Summoned" creature?
They are definitely a controller secondary. Their spirit doesn't really control in the same way that summoned creatures do. They are completely immune to area attacks and a large number of attacks that target them specifically don't do enough damage to destroy them. Not being a creature, they can't have status effects applied to them and they can be recreated at will. So, there isn't much incentive for the enemies to try to take it out and waste their attacks.
Meanwhile, with Wizard's summoned creatures, they do significant damage with low hitpoints. Might as well spend an attack destroying them since destroying them effectively ends a daily power. And I tend to define control as anything that causes the enemies to not make optimal choices. In the case of summoned creatures, the enemy is forced to attack a creature other than one of the PCs as their action to avoid taking damage.
Controlling and Defending are very similar. Controller prevent enemies from making attacks on the party. Defenders force the enemies to attack THEM.