Spelthorne was a hundred (dated subdivision) of the historic county of Middlesex, England.

It contained these parishes and settlements:[5] The present-day district of Spelthorne in Surrey amounts to about 59% of the hundred.

A decennial table for each parish is published in the Victoria County History series.

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.

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).