"Tacroy" is the name of his astral self, not of his physical self, and in fact he himself doesn't know that his astral name is Tacroy until Christopher tells him during their first in-the-flesh meeting. He appears to be a young man with brown skin, hazel eyes, and tightly-curled pale brown hair, wearing a green worsted suit.
As an astral traveller, only his spirit travels through the Passage into other worlds; his body remains behind in a deep trance, kept warm by blankets and hot water bottles. A medium sits by his body the entire time keeping an eye on him and playing music to give his spirit a thread to follow home; he tells Christopher that he has a clause in his contract stipulating that the musician must be a beautiful and agreeable young lady. When he first meets Christopher, it's a young lady who plays the harp.
Christopher can bring him more solidly into a world he's visiting, but this has the result of making his body back at home grow insubstantial. The first time Christopher tries it, it panics the young lady with the harp, who refuses to work for him again; her replacement, who Tacroy must accept since it's at short notice, is - by Tacroy's account - a stern young lady with a voice like a hatchet who plays the flute like someone using wet chalk on a blackboard. Uncle Ralph later finds him a grandmotherly lady who plays the violin quite well.
Tacroy occasionally alludes to a young lady who was once the light of his life, who also played the harp and was the best medium-musician he ever had; he dodges the question of how they came to be parted.
He tells Christopher that he was a foundling child, discovered as a baby on an island and raised by an agreeable and devout Sea Captain.
Like Christopher, he is a keen cricketer. His talent is in bowling; he has a good slow leg-spin. He is a member of the local team. He teaches Christopher a lot about the game in spare moments during their trips.
The name of Tacroy's physical self, and the identity of his young lady, are spoilers for ''The Lives of Christopher Chant''.