Ambassador Trentino is the main antagonist in The Four Marx Brothers' 1933 feature film, Duck Soup. He is the Ambassador from the country of Sylvania to the country of Freedonia (supposedly European and both completely fictional).
He was portrayed by Louis Calhern.
Secretly, he plots to foment revolution in Freedonia, leaving it open to conquest by his country. He becomes the nemesis of Freedonia's newly appointed President, Rufus T. Firefly. Since Firefly is played by Groucho Marx, this virtually guarantees that the rest of his existence will be absolutely miserable. He is pompous, self-assured and easily irritated - especially by Firefly. His secretive manipulations of national relations, matched by the blistering incompetence of the Freedonians, parodied the attitudes many felt about world leaders during the First World War.
Trentino in Duck Soup
As the movie starts, Trentino's espionage plans are going poorly. Despite what was essentially a vow by Firefly to drive the debt-ridden Freedonia further into debt and ruin, the new president has the firm support of the people, ending talk of revolution. His personal spy, an actress named Vera Marcal, can neither find dirt on Firefly nor persuade Freedonia's wealthy sponsor, Mrs. Gloria Teasdale (played by eternal Marx Brothers' straight-woman Margaret Dumont) to marry him, thus ending Freedonia's economic lifeline. Trentino has two spies in reserve, trying to gather rumors or scandal about Firefly. Unfortunately for him, the two spies in question are Chicolini (Chico Marx) and the silent Pinky (Harpo Marx) who frustrate him to no end with their complete inability to shadow Firefly. Despite their idiocy (or perhaps because of their idiocy), Firefly ends up appointing Chicolini his Secretary Of War, while Firefly's personal assistant Bob Roland (Zeppo Marx) insists that they get rid of the scheming Trentino. A plot to have Firefly insult Trentino into slapping him, and thereby grant them an excuse to expel Trentino, backfires when Firefly slaps Trentino. Repeated attempts at peace-brokering by Mrs. Teasdale are repeatedly thwarted by Firefly's antics. A scheme by the now war-hungry Sylvanians to get Freedonia's secret battle plans ends in disaster, and they don't get the plans either. Instead, Chicolini is exposed as a (very ineffective) spy and put on trial. Somehow, despite high treason, Chicolini and Pinky join Roland and Firefly in an insane defense of Freedonia at the frontlines, where Firefly is more than willing to have every last man fall - except of course himself. Continually blundering the defenses, and even shooting their own men from behind, the Freedonians manage to capture Trentino, whom they pelt mercilessly with fruit, until Mrs. Teasdale begins to sing a victory aria, at which point they instead pelt her with fruit.