In a large mixing bowl, combine the Greek yogurt, shredded cucumber, lemon juice, dill, garlic powder, and salt and pepper. Stir until smooth and creamy.

Add shredded chicken, diced red onion, sliced Kalamata olives, and crumbled feta cheese to the tzatziki mixture. Gently fold until well-coated.

Taste the mixture and add more lemon juice or seasoning if needed.

Cover the mixing bowl with plastic wrap and refrigerate for at least 30 minutes.

Before serving, stir gently and garnish with extra crumbled feta, dill, or olive oil.