A mysterious $7 billion estate-tax payment was made to the US Treasury in February 2023, with the identity of the deceased billionaire unknown. An anonymous source suggested that the payment came from the estate of Fayez Sarofim, a billionaire who died in May 2022 and was known for his private investment management firm. The article explores the possibility that Sarofim intentionally chose not to avoid the estate tax, despite having the means to do so. The payment is the largest estate-tax payment in modern history, and its significance is being debated in the context of US tax policy and wealth inequality.