What is only marx brother not in any marx brothers films?

Herbert Marx, also known as Zeppo Marx, was the youngest of the Marx brothers and the only one who did not appear in any Marx brothers films. Instead, he worked behind the scenes, helping to manage the brothers' careers and serving as their agent. Zeppo also pursued other interests, including inventing and manufacturing a cervical collar that was used to treat neck injuries. Later in life, he switched careers and became a talent agent, representing stars like Lana Turner and Soupy Sales. Despite not appearing in the films, Zeppo was an integral part of the Marx brothers' success and legacy.