Danilo Aleksandar Petrović-Njegoš (Anglicised: Daniel Alexander Petrovich-Nyegosh) (June 29, 1871 – September 24, 1939) was the Crown Prince of Montenegro. He was eldest of the sons of King Nikola I Petrović-Njegoš of Montenegro and Queen Milena Vukotić. From March 1, 1921 - March 7, 1921 Danilo was the self-assumed King of Montenegro leading an unrecognised Government-in-exile. On March 7 1921 for reasons which are still unclear Danilo abdicated his royal claims and headship of the royal house in favour of his nephew, Prince Michael Petrović-Njegoš of Montenegro.

Prince Danilo resurfaced in 1934 when he sued Metro-Goldwyn-Mayer for libel and collected $4,000 in a Paris court for the false-depiction of him in the first version of the film The Merry Widow. In the film "Prince Danilo of Montenegro" seduces a commoner and then rejects her because it could impoverish the royal treasury. He then regrets his actions and tries to win her back but fails to convince her of his true love. The film bears no relation to reality. The film was re-shot this time featuring a toned down "Captain Danilo".

The real Prince Danilo was married to Duchess Jutta of Mecklenburg (1880-1946) the daughter of Adolf Friedrich V, Grand Duke of Mecklenburg-Strelitz, but the marriage was childless. After he abdicated in 1921 he spent most of his life living in Nice.