Casteel is described as beautiful on several instances. He has dark, thick hair that curls at the nape of his neck and often falls forward, brushing equally dark brows. His cheekbones are high and wide, nose surprisingly straight for a guard. His square jaw is firm, and his mouth well formed. When he smiles, the right side of his lip curves up, and a deep dimple appears. Sometimes, dimples appear on both cheeks when he is freely smiling and able to show his fangs. He is also mentioned multiple times, to be very tall, roughly larger than six feet. He possesses captivating eyes which are a pool of gold and honey. He smells of cinnamon, dark spices, and pine.