Dorothy Arnold (18?? - 1910?) was a U.S. socialite who disappeared.

Dorothy Arnold was a daughter of wealthy importer Francis Arnold and his wife and niece of Rufus Peckham. She had graduated from Bryn Mawr College and unsuccessfully tried her hand as a writer.

Arnold left her parent's home in Manhattan, New York City on the morning of December 12, 1910. She was going to go shopping for a dress for a party. Acquaintances she met in the Fifth Avenue later described her a cheerful. She was last seen in a candy store at the corner of the Fifth Avenue and 27th Street, going to a bookstore. At night she failed to come back for a dinner. First her family phoned her friends in case she had decided to visit any one of them.

Arnolds feared that the case could be socially embarrassing - Dorothy had eloped and spent a week with George Griscom, Jr a month before. Death would have been preferable to a social gaffe. Instead of calling the police, they made discreet enquiries through John S. Keith, a family friend, and hired Pinkerton detectives to investigate the disappearance. Keith searched hospitals, morgues and jails in New York, Boston and Philadelphia for three weeks until he had to give up.

Arnold family turned to police six weeks after their daughter had disappeared. In a press conference, Francis Arnold said he believed that Dorothy might have been attacked and killed in Central Park and her body thrown into the reservoir. Although he refused to mention Griscom's name, journalists tracked him down.

Griscom, who was in Naples at the time, sent a telegram where he stated that he did not know where Dorothy was. In January 1911 Dorothy's mother and his brother John travelled to Italy to forcibly interrogate him, without results. Griscom could only hand over a letter where Dorothy had mentioned her depression over a story she had written and which had been rejected by a magazine.

Intrigued by the disappearance, and probably to quell any suspicions he might have something to do with it, Griscom later spent thousands of dollars searching for Dorothy - without results. He paid for ads in major newspapers where he asked Dorothy to come home.

Rumors and theories abounded. Dorothy was rumored to be in a hospital somewhere with total amnesia but there was nobody that matched her description. Others suggested she might have died of botched abortion. Some of Dorothy's friends suspected that Dorothy might have committed suicide because Griscom had refused to marry her. Most widespread rumor was that she had become pregnant out of wedlock, the family had banished her to Switzerland and the search was a very elaborate ruse to hide the scandal. Others said that she had simply decided to disappear.

There were numerous "sightings" or Dorothy all over the USA but all of them proved to be false. In 1916 a Rhode Island convict claimed that somebody who had resembled Griscom had paid him $150 to dig a grave for Dorothy in a cellar of a house near West Point. Police did not find any sign of any corpse.

Francis Arnold died 1922; He had spent over $100.000 trying to find Dorothy and in his will he stated that he was satisfied that his daughter was dead. His wife died 1928.