In February 2011, Markstein, who had a history of strokes, suffered what his daughter called "an incident that caused him to be in and out of hospitals for several weeks", and the following month "suffered a massive stroke while in the hospital. This caused him to be paralyzed on his left side." He died of respiratory failure in March 2012. In 2012, Markstein's family announced plans to continue updating Toonopedia through new articles written by fans, but the site has yet to be updated since February 2011.