Spelthorne was a hundred (dated subdivision) of the historic county of Middlesex, England. It contained these parishes and settlements: The present-day district of Spelthorne in Surrey amounts to about 59% of the hundred. The eastern parts since 1965 form parts of the London boroughs of Hounslow and Richmond upon Thames.

Demography

A decennial table for each parish is published in the Victoria County History series. By 1891 the Hundred was legally moribund, having already been de facto moribund. The population of the north-eastern six parishes has been greater than the south-west seven since an unknowable point in time between the 1831 and 1841 censuses. A summary is: Relative to the county as a whole, the hundred (one of six) had 12.9% of its 181,320 acres. In 1801 it had 1.3% of the 818,129 people recorded as living in Middlesex; in 1901 it had 1.6% of the 3,585,323 people stated in the census to be living in the county (including in the County of London parts which once lay in Middlesex).