Glentham is a village and civil parish in the West Lindsey district of Lincolnshire, England. It is situated on the A631, 6 miles (9.7 km) west from Market Rasen, and 2 miles (3.2 km) east from Caenby Corner and the A15.

The civil parish includes the hamlet of Bishopbridge, on the A631 2 miles (3 km) east of the village, and the eastern part of the hamlet of Spital-in-the-Street on the A15 (Ermine Street) 2 miles (3 km) west of the village.

The Oxford Dictionary of English Place Names gives the derivation of the name Glentham as glente + hām, meaning either ″homestead frequented by birds of prey″ or ″homestead at a lookout place″. Caenby is said to probably mean ″farmstead or village of a man called Cāfna or Kafni″.

Glentham was mentioned in the Domesday Book of 1086, as being in the Aslacoe hundred in the West Riding of Lindsey. It had a total population of 64 households (very large for the time) with tax assessment of 8 geld units (again very large). Land in Glentham was held by four separate lords before the Norman Conquest and three afterwards:

Lord in 1066: Lincoln St Mary, bishop of. Lord in 1086: Lincoln St Mary, bishop of. Tenant-in-chief in 1086: Lincoln St Mary, bishop of.

Lord in 1066: Thorgisl. Lord in 1086: Rainfrid. Tenant-in-chief in 1086: Ivo Tallboys.

Lords in 1066: Estan of Farningham; Wulfmer. Lord in 1086: Wadard of Cogges. Tenant-in-chief in 1086: Bishop Odo of Bayeux.

The first bombs to land in Lincolnshire were on the night of June 5 1940, with two HE bombs.