Marius Aventicensis was a sixth-century bishop and historian born near Autun. Appointed to lead the see of Aventicum in 574, he eventually moved his seat to Lausanne as his original city declined. He is primarily recognized for composing a concise chronicle that details historical events from 455 to 581. This work provides significant insights into the history of the Burgundians and Franks, while also offering an early written mention of a smallpox epidemic in Gaul and Italy.