Sir John Spencer (1524 – 8 November 1586) was an English nobleman, politician, knight, sheriff, landowner, and Member of Parliament.

Spencer was the son of Sir William Spencer of Wormleighton Manor, Warwickshire, and Althorp, Northamptonshire, and his wife Susan Knightley, daughter of Sir Richard Knightley of Fawsley, Northamptonshire.

He was elected as a Knight of the Shire (MP) for Northamptonshire in April 1554, and again in 1558.

They had five sons and six daughters, including Sir John Spencer died on 8 November 1586, and was buried with his wife Katherine Kitson in St Mary the Virgin Church, Great Brington (the parish church for Althorp) where his epitaph lists his sons, his daughters and their husbands.

He was succeeded by his eldest son, Sir John Spencer (died 1600).