Main characters The characters are named here as they are in the revised edition of the original book, and its sequels. The family name in the 1924 original edition is Cordyce rather than Alden.
Henry James Alden is the eldest of the Alden children; in most books of the series, Henry is 14 years old (13 in the 1924 edition). He is shown to be calm, hardworking, rational, humble and very protective of his younger siblings. Henry also shows a knack for repairing things and is a natural athlete. In Warner's original books, Henry ages and eventually goes off to college in
The Lighthouse Mystery.
Jessie Alden (
Jess in the 1924 original edition) is usually 12 years old and is the older sister. She often acts motherly towards Benny and Violet and even Henry. She is often responsible for cooking. Jessie is described as being very tidy and organized. She is sometimes called Jess, but is mostly referred to as Jessie. Jessie is not afraid of anything, adores the color blue, and is very strong.
Violet Alden is 10 years old in most of the books. She is the most sensitive of the children and is skillful at painting and sewing. Violet can frequently win over grouchy characters and is good with animals. She is often shy and loves playing the violin. Violet's favorite color is violet or purple and she often wears one of those colors. Violet is the shyest of all the children, and sometimes helps Jessie take care of Benny.
Benjamin "Benny" Alden is the youngest child at 6 years old (5 in the original 1924 edition). He celebrates his seventh birthday in
Surprise Island and continues to age throughout the original series, until he is old enough for a department store job in the last original book,
Benny Uncovers a Mystery. Benny is known for his love of all food and the cracked pink cup he found in the dump. His endearingly childish qualities and comments along with his enthusiasm make him a favorite among young readers. Benny loves Watch dearly and was also the one who named Watch.
Watch is the dog of the Boxcar children. He acted as a "watchdog" when they lived in the boxcar and protected them. Watch was originally owned by a wealthy lady but ran away and was adopted by the Alden children. The lady was so charmed by the children that she let them keep him. Watch is a
Wire Fox Terrier (an
Airedale in the 1924 edition), and the children found him while Henry was away at work. Watch had a thorn in his paw, and Jessie removed it. Because of this, Watch became known as her dog. In subsequent books, his bed is in Jessie's bedroom.
James Henry Alden is the wealthy and kind grandfather of the Alden children, allowing them a lot of freedom and always offering them advice. He takes care of the kids after the death of their parents. At first, the kids thought their grandfather was mean since he did not like their mother, and so they ran away from him. However, they later realized his goodness and came to live with him. James Henry Alden also organizes the Field Day competitions.
Dr. Moore (Dr. McAllister in the original 1924 edition) is the man who gave Henry a job and checked Violet when she was ill. He is the same person who connected Henry, Jessie, Violet, Benny and Watch with their grandfather.
Secondary characters Mrs. McGregor: The Aldens' housekeeper, her husband was first seen in the third book of the series.
Mr. McGregor mows the lawn and he is Mr. Alden's conductor. He is also married to Mrs. McGregor.
Mike is Benny's best friend and appeared in
Surprise Island.
John Joseph "Joe" Alden and Alice: The children's cousins/aunt and uncle, Joe was first seen in the second book of the series,
Surprise Island. Alice was first introduced in
The Yellow House Mystery; she also married Joe in the same book. They moved to a new house in
The Mystery of the Singing Ghost. They adopted Soo Lee from Korea.
Aunt Jane and Uncle Andy: The children's great aunt (Grandfather Alden's sister) and her husband, Aunt Jane was once unkind, but was changed in
Mystery Ranch, the fourth book of the series.
John Carter: An employee of the children's grandfather, he does investigation and carries out the children's grandfather's wishes "off camera". He has a secret soft-spot for Jessie.
Lars Larson: A fun middle-aged man and a friend of Grandfathers, Lars was first seen in
Blue Bay Mystery. ==Animated film==