Millyn is of average height, with short black hair and dark brown-grey eyes. She has a thin, youthful face that always seems to hold an expression of mischievousness. She is quite muscular, as she has had to carry heavy parcels for her job, and also because she likes to climb onto the rooftops of Bree, which requires a considerable amount of strength. She has very pale skin, which is not too noticeable.

When she's working, Millyn usually wears her something that resembles a post office uniform: a blue waistcoat over a white shirt, navy leggings, and a small blue hat. She wears a blue satchel on her back to carry all the letters she needs to deliver. She also carries a precautionary knife, in case someone decides to attack her - it is quite small and doesn't look like it would help in combat. When she is not working, she wears a grey tunic with a long blue overcoat - she likes to wear it so that if by chance a gust of wind blows, she will look heroic, even though in reality that is only a vision.