Preheat the oven to 375°F and line a baking sheet with parchment paper.
In a large bowl, combine the ground beef, feta cheese, kalamata olives, oregano, breadcrumbs, egg, onion, garlic, salt, and black pepper. Mix gently with your hands until the ingredients are evenly distributed.
Divide the mixture into four equal portions and shape each into a small loaf about 3 inches long. Place the loaves on the prepared baking sheet.
Spread 2 tablespoons of ketchup over the top of each mini meatloaf, using the back of a spoon to coat evenly.
Bake for 25 to 30 minutes until the internal temperature reaches 160°F and the glaze has thickened slightly.
Remove from the oven and let the meatloafs rest for 5 minutes before serving.