Troilus de Mesqouez (1536–1606) was a French noble (Marquis de La Roche-Helgomarche) and served as Viceroy of New France. He initiated the first attempts to settle Sable Island, a small island off the Canadian province of Nova Scotia.
de Mesqouez was born in Mesgouez en Ploumoguer to parents Guillaume de Mesgouez and Françoise Campir. He was granted the title of Viceroy of New France in 1578 by Henry III of France and around 1598 or 1599 sent settlers (mainly criminals) and soldiers to Sable Island to establish a fishery and fur trading post. Poorly planned, the settlement failed and was abandoned around 1602–1603.