Thatcham is a town in the ceremorial county of Berkshire, England. It is located 3 miles (5 km) east of Newbury and 15 miles (24 km) west of Reading. It covers about 8.75 square miles (22.7 km²) and has a population of 23,000 people (2003).

It lies on the River Kennet, the Kennet and Avon Canal, the A4 road and the course of a Roman road.

The area has evidence of occupation dating from prehistoric times, and it is claimed as being one of the oldest (if not the oldest) continuously inhabited place in Britain. The well-preserved remains of a Mesolithic settlement dating from 7,700 BC have been found in its vicinity. There is also evidence of Bronze and Iron Age settlements and of a Roman town.

The name may have been derived from that of a Saxon chief called Tace (or perhaps Tac or Tec), who established a village in around 500. The settlement was known as Taceham - ham meaning village in Saxon. It is also possible that the name may have come from the Saxon thaec (thatch). Wherever it came from, the name Taceham persisted until after the Norman Conquest in 1066 before going through several minor changes until the current one was adopted in the 16th century.

There is a Norman parish St Mary's Church which was largely reconstructed in 1857. This is believed to be built on the same site as an earlier Saxon church. It was also previously known as St. Luke's.

In 1121 King Henry 1st founded the great Abbey of Reading and endowed it with many gifts of land, including the Manor of Thatcham. At the same time Thatcham Hundred ceased to exist, the western party being transferred to Farcross Hundred, and the remainder to the Hundred of Reading.

In 1141 Thatcham Church, previously the property of the Diocese of Salisbury, was granted to Reading Abbey by the Empress Mathilda, who at the same time confirmed her father's gift of the manor to the Abbey.