William Beech is a fictional character from the novel "Goodnight Mister Tom," written by Michelle Magorian. He is a young boy who is evacuated from London during World War II to escape the dangers of the Blitz. William comes from a troubled background, having faced neglect and abuse from his mother. In the countryside, William is taken in by Tom Oakley, a kind and reclusive man. Their relationship develops as Tom helps William heal from his past traumas, teaching him about love, trust, and the joys of life outside the city. The story highlights themes of friendship and resilience.