Alexander of Lincoln was a medieval English Bishop of Lincoln, a member of an important administrative and ecclesiastical family. He was the nephew of Roger of Salisbury, a Bishop of Salisbury and Chancellor of England under King Henry I, and he was also related to Nigel, Bishop of Ely. Educated at Laon, Alexander served in his uncle's diocese as an archdeacon in the early 1120s. Unlike his relatives, he held no office in the government before his appointment as Bishop of Lincoln in 1123. Alexander became a frequent visitor to King Henry's court after his appointment to the episcopate, often witnessing royal documents, and he served as a royal justice in Lincolnshire.

Newark Castle, in Newark-on-Trent in the English county of Nottinghamshire, was founded in the mid 12th century by Alexander, Bishop of Lincoln. Originally a timber castle, it was rebuilt in stone towards the end of the century.