Seth is a 13 year old spacebot with light-fair skin, blonde hair and blue eyes. He wears a light red tight zentai suit, pale red wristbands with a red star on both, red shirt with a pale red star, red shorts, pale red cap sleeves and a pale red belt with a bright red star in it and red boots with a red star on both. His magic powers has red stars in it. He is the youngest of three brothers and his signature color is red.
In the TV series, Seth forgets something, and he is slightly clumsy and forgetful. He is the youngest, or the 'baby' of the Space Brothers. He also has a crush on Sally.