In a large mixing bowl, combine the olive oil, minced garlic, salt, pepper, paprika, cayenne pepper, and onion powder.
Add the chicken thighs to the bowl and toss to coat the chicken with the marinade. Cover and refrigerate for at least 30 minutes, or overnight for maximum flavor.
Preheat your grill to medium-high heat (375F)
Once the grill is hot, remove the chicken from the marinade and discard any remaining marinade. Grill the chicken for 4-5 minutes per side, or until it reaches an internal temperature of 165 degrees Fahrenheit.
Once the chicken is cooked through, remove it from the grill and let it rest for a few minutes before slicing or serving.