When I was a kid, we had a big bard owl that discovered the abundant food source at our bird feeder. He hung out for the last half of winter every couple of days... waiting from a about 15 yards away. All you would see was a blur and a few feathers floating to the ground as it would take birds or a squirrel right off the feeder.
About 7-8 years ago we had a Red tail hawk build a nest in one of the largest pines in the yard. She did some real damage to my fox squirrel community that frequented the bird feeder but she never took any directly from the feeder that I saw but would just hammer the ones crossing the yard to and from it.
Both of the stories above were fascinating to watch from the window of the house.