Base Class: Barbarian
While not evil per se, your acts of consumption would be shunned by most. To adventure as a Cannibal, you have learned to hide your customs from commoners, but partake openly in front of enemies and trusted allies.
All Consuming Rage
Starting at 3rd level, during rage, when you reduce a hostile opponent to 0 hit points, you gain temporary hit points equal your barbarian level + Constitution modifier (minimum of 1).
Biting Rebuke
At 6th level, while in rage you can make a bite attack as a reaction when struck in melee range by an opponent. This attack deals 1d6 + Strength modifier piercing damage, and on a hit the opponent must succeed on a wisdom save DC 16 or be frightened. They may try again if failed at the beginning of their next turn to overcome the frightened condition.
Heart of Enemies
Beginning at 10th level, by consuming a heart of a humanoid you have participated in slaying within the past hour, you regain your full hit points as if finishing a long rest. You must finish a long rest to regain the use of this feature.
Spirit of the Slain
At 14th level, by channeling the spirits of those you have eaten, you deal double critical damage on a critical hit. You can only do this a number of times each long rest equal to your proficiency bonus, and only once per turn.