Zekial Marko (October 21, 1933 – May 9, 2008) was an American writer who specialised in crime stories, often under the pen name of John Trinian. He was arrested during filming of Once a Thief and spent some time in prison.

He died of complications related to emphysema on May 9, 2008, in Centralia, Washington. Zekial Marko was born as Marvin Leroy Schmoker on October 21, 1933, in Monterey County, California to Ruth Halverson and Wallace Cyril Schmoker. As children, Marko and his brother, Kenn Davisl Kenn were neighbors of John Steinbeck in Salinas, California.