Marcus Ewert, previously known as Mark Ewert, is an American writer, actor and director, living in San Francisco.

Marcus Ewert began making and appearing in films in the 1990s. He has appeared in the Gus Van Sant short film Four Naked Boys and a Gun, in Sadie Benning's Flat Is Beautiful, and the movie Frisk by Todd Verow. In 2008, the feature filmThe Lollipop Generation by G.B. Jones was released starring Mark Ewert in a lead role, alongside Jena von Brucker, Vaginal Davis, Calvin Johnson, Joel Gibb and Scott Treleaven.Davies, Jon, "Images fest: GB Jones", Xtra, 27 Mar, 2008

His first collaborative work as a director was with Joshua Tager: together they made A New Flag. He then began collaborating with David Crystallah, making several films together in 1998. These films played frequently at film festivals. In 1999, he began working with David Cutler. The two created Piki & Poko, first released in the 2000s. These animated short flash cartoons created for the Internet were immediately successful and have been distributed by Mondo Mini Shows. There have been thirty three episodes scripted and twenty eight have been released. The episode entitled Taking The Dare! also appeared on Season 6 of the Emmy Award winning PBS series, Independent Lens. Lisick, Beth, "PBS in the Mission", SF Gate, Nov. 3, 2004 The series began airing on the Logo channel in 2008, as part of the Alien Boot Camp animation anthology.