Final answer:
Boo Radley became an outcast due to his reclusive childhood and the key event of stabbing his father with scissors, which led to him becoming a local legend.
Step-by-step explanation:
The question regarding Boo Radley focuses on the character from Harper Lee's novel To Kill a Mockingbird. Events in Boo Radley's childhood, such as being kept inside by a strict father, led to his reputation as an outcast in Maycomb. The major event that cemented his status as a neighborhood legend was when Boo was accused of stabbing his father with a pair of scissors, which resulted in his further seclusion and the town's fear and fascination with him.