Daniel Maurice Alan Macmillan, Viscount Macmillan of Ovenden (born 9 October 1974) is the heir apparent to Alexander Macmillan, 2nd Earl of Stockton. As heir apparent to an earldom, he holds his father's secondary title of Viscount Macmillan of Ovenden as a courtesy title.
Viscount Macmillan is a great-grandson of the former Prime Minister Harold Macmillan, 1st Earl of Stockton.
He grew up at Birch Grove, the family home in Sussex, and was educated at Eton College, and the Parsons School of Design, New York.
In 2003 he designed and launched the Zoltar fashion label with Kieron Livingstone as creative director. Prior to that, he had his own fashion label, 'Macvillain'. 
In addition to his clothing label, Macmillan has worked as a model, an actor, and photographer. He is said to have dated Kate Moss and Jade Jagger.
Macmillan does not plan on entering the family publishing business, after his father sold it to a German publisher in the 1990s. He is heir to a £200 million fortune.