One of my first 5E characters was a Human Variant War Cleric. He had a 16 Strength, 16 Wisdom, and Great Weapon Master at first level.
In his first real action, he came across an ogre guarding a cave. He cast bless. And then snuck up on the ogre, getting a surprise round, and then beat the ogre in initiative.
He used his war cleric ability to make an attack as a bonus action during the surprise round, so he was doing: 2 attack rolls of d4+d20 to hit versus AC 11 and each hit did 2d6+13 damage. He hit twice. And did about 40 damage.
Then, in the next round, because he won initiative, he went before the ogre. He attacked and missed, but then used the War Cleric ability a second time and did about 20 damage - killing the ogre. Solo, At 1st level.
As we were new to the edition, it sparked some controversy about how broken clerics were. That talk faded at about 5th level, but up and until that point the group was quite upset that the war cleric was so overpowered. After 5th he was effective, but not seen as overpowered (until he multi-classed to paladin.