Thomas "Tom" Robinson is a character from the 1960/1962 novel/film To Kill A Mockingbird. He is metaphorically and symbolically one of the "mockingbirds" in the novel, in the sense that he is a kind, innocent, and harmless man who doesn't think twice about helping others. But since he's African-American, that instinct lands him in jail, accused of a serious crime.
In the story
Tom Robinson a poor black man was accused of raping Mayella Ewell and defended by Atticus in the story.
There is profound evidence found in the trial to say that Tom is not the one who abused Mayella. For example, Mayella had bruises on her right side (from her point of view), while Robinson could only use his right hand (from his point of view) in order to harm Mayella, because his left hand was ruined from a childhood accident. Later Tom is said to be guilty by the Juries and while being led to prison tries to run away. This leads to his death because he decided to make a run for it over the prison fence. As he is climbing, he is shot seventeen times. The guards told Atticus that if he had both arms, he would have escaped. Atticus and Calpurnia told his wife Helen he died.