Harold Levinson is the son of the late Isidore Levinson, millionaire dry good merchant, and Martha Levinson. He is the brother of Cora, the brother-in-law of Robert Crawley, Earl of Grantham, the uncle of Mary Crawley, Edith Crawley, the late Lady Sybil Branson, and an unnamed deceased nephew, the uncle-in-law of Matthew Crawley and Tom Branson, and the great-uncle of Miss Sybil Branson and George Crawley Crawley.
In 1920, Martha informed Violet, Mary, and Cora, that Harold was doing "something with yachts". He was making them bigger or faster, she was not sure which, and that he far was "too busy" to find out whether he was happy or not. According to Violet, the Crawley family "never see him" which, according to Martha, is because he "hates to leave America."
When Mary discusses with her grandmother Violet the possibility of asking Martha Levison for the money to save Downton, she describes Harold as not needing the money, as he is "rich as Croesus". Cora learns that Mary is planning to ask her for the money and disapproves. She not only thinks it undignified, but she believes that their financial problems are their own. She says that they are not her mother or Harold's fault, and they should not have to pay for them.
As it turns out, Martha later tells them that her husband tied up the money so that Martha gets the interest, but the capital is held for Harold, as her husband believed that Downton had gotten enough of his money.
- It is currently unknown if Harold is married and has children.
- Episode 3.02 (mentioned)(Mentioned only)