Nyall held the rank of moff and worked for the Galactic Empire. In the year 5 ABY, as the New Republic began to take shape, its representatives compiled a list of high-ranking Imperial officers they wanted to capture, and Nyall's name was on it. Shortly after this list was created, pilot Norra Wexley led a team of New Republic agents who successfully apprehended Nyall. Following his capture, the moff's name card was added to the collection kept on the crew's starship, known as the Halo, along with the cards of other captured Imperials. When adding another card to their collection, Temmin Wexley, a member of the team, recalled the capture of Nyall.
Chuck Wendig mentioned Nyall in Aftermath: Life Debt, which was released in 2016 and served as the second book in the Star Wars: The Aftermath Trilogy.