Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius).
In a large bowl, whisk together the olive oil, lemon juice, minced garlic, oregano, thyme, salt, and pepper to create the marinade.
Add the chicken thighs to the bowl and toss until each piece is evenly coated.
Transfer the marinated chicken to a 9x13 inch baking dish, arranging the pieces in a single layer.
Scatter the sliced red onions and kalamata olives over and around the chicken.
Bake for 25 to 30 minutes, or until the internal temperature of the chicken reaches 165 degrees Fahrenheit (74 degrees Celsius).
Remove from the oven and garnish with crumbled feta cheese before serving.