Place the hard-boiled eggs in a large bowl and mash with a fork or potato masher to desired consistency.
Add Greek yogurt, mayonnaise, Dijon mustard, garlic powder, salt, and pepper. Mix until well combined.
Fold in chopped celery, green onions, and dill if using.
Serve chilled on whole grain bread, lettuce wraps, or in a bowl with crackers or veggies.