Matthew (Moose) Flanagan:
Moose is a twelve year old boy who moves from Santa Monica to Alcatraz with his family because his father gets a job as an electrician and a guard. In Al Capone does My Shirts, Moose is 5' 11" and loves playing baseball. He used to play baseball with his friends before he moved, and misses them dearly. Moose has golden brown hair with brown eyes. When his mother gets a job Moose begins to spend a lot of time with his sister Natalie.
Natalie Flanagan:
Natalie is Moose's "younger" sister who unlike Moose has bright blue eyes. Natalie is actually fifteen in the book, but her mother celebrates her birthday every year as her tenth birthday. Natalie has a severe case of Autism, however it was not diagnosed in 1935 so her family has been struggling to find a place that can get Natalie help. Natalie is one of the main reasons that the Flanagan's moved to Alcatraz. In order for Natalie to go into the Esther P. Marinoff program the family needed to move to San Francisco. Natalie likes to spend time with her brother, and count things like stones and feathers. She has a special button collection that she is obsessed with. Natalie also throws tantrums.
Piper Williams:
Piper is the wardens daughter. Piper is extremely bossy and always coming up with schemes that are against the rules. She goes to school with Moose in San Francisco. She is very pretty but is often found as an annoying brat.
Annie:
Annie is twelve years old. She is an overweight girl with yellow hair. Annie is the only girl on the island that plays baseball and she is a great pitcher.
Jimmy and Theresa Mattaman:
Jimmy is twelve and Theresa is seven years old. Like there parents both children have curly black hair. Jimmy and Theresa are excited that they will have another sibling soon. While Jimmy and Theresa are brother and sister they both have different interests. Jimmy is absolutely terrible at baseball and Theresa treats Natalie as a sister.
Scout Mcllevy:
Scout is a boy that goes to school with Moose and Piper. He is a skilled baseball player, and he is in charge of setting the school baseball games up every week. Scout really wants a baseball that Alcatraz Prisoners played with. Moose eventually gets him one after searching for days. Scout is also responsible for switching the baseball games to Tuesday so that Moose can participate.
Cam Flanagan:
A fair and kind man that loves to play baseball. He loves his children Moose, and Natalie Flanagan very dearly. He is hired to work on Alcatraz as an electrician and prison guard. He took the job so that his daughter Natalie could join the Esther P. Marinoff Program in San Francisco.
Helen Flanagan:
A nice caring women who can be strict at times. Mrs. Flanagan makes quite a bit of rules that she expects her children to follow. Helen later gets hired to teach people to play the piano in San Francisco. As a result Helen tells Moose that he is responsible for taking care of Natalie when she is gone. Moose tells Scout that he can't play baseball with him because of Natalie. Scout had just finished changing the game dates and was very angry to hear this. For awhile they didn't talk before they made up. Helen also took Natalie's buttons away in an attempt to "cure" her. Helen had good intentions and just wanted to help Natalie.
Warden Williams:
Warden Williams is incharge of the prisoners on Alcatraz island. He is very strict, and makes a lot of rules everyone on the island needs to follow. Moose is very scared of him because he keeps threateninghis fathers job when Moose does something wrong. Most of the Alcatraz inhabitants are also scared of the Warden for many different reasons. Moose asks him to help Natalie but the Warden basically says know your parents will figure something out.
Prisoner 105 "onion":
Convict 105 started to develop a relationship with Natalie. When Moose found out he thought that they were having a romantic relationship. Natalie refers to him as his number 105. THe convict also gives Moose a baseball which he later gives to Scout.
Mr. Purdy:
Mr. Purdy is the head of the Esther P. Marinoff School. He meets with the Flanagans on many occasions. He excepts Natalie for a trial run but after a day calls and says that she needs to be picked up. Mr. Purdy recommends taking Natalie to see Mrs. Kelly. Mrs. Flanagan having seen this many times before holds her ground and argues with Mr. Purdy. Eventually she submits and they go see Mrs. Kelly. He later starts the program for older children when Al Capone gets involved making Natalie the first student.
Al Capone:
Al Capone was a convict at Alcatraz who helped Moose get Natalie excepted into the program. He also was apart of Piper's money making schemes. He lived on Alcatraz from 1934 to 1939.
Mrs. Kelly:
Mrs. Kelly became Natalie's private teacher after Mr. Purdy removed her from the program. Mrs. Kelly was responsible for helping Natalie develop social skills. Natalie develops basic humor and adds new words to her vocabulary due to Mrs. Kelly's teachings.