The 1942 Salisbury by-election was a by-election held for the British House of Commons constituency of Salisbury in Wiltshire on 8 July 1942. It was won by the Conservative Party candidate John Morrison, later Baron Margadale.

The seat had become vacant on the death of the 55-year-old sitting Conservative Member of Parliament (MP) James Despencer-Robertson. He had won the seat at a by-election in 1931, having previously been MP for Islington West from 1922 to 1923.

The Conservative candidate was 36-year-old John Morrison.

During World War II, most by-elections were unopposed, since the major parties had agreed not to contest by-elections when vacancies arose in seats held by the other parties; contests occurred only when independent candidates or minor parties chose to stand, and the Common Wealth Party was formed with the specific aim of contesting war-time by-elections.

In Salisbury, there were two independent candidates: William Reginald Hipwell, editor of Reveille, a " barrack room newspaper for the fighting forces",^[1] stood as an Independent Progressive and J. D. Monro as an "Independent Democrat".

On a greatly reduced turnout, Morrison held the seat for the Conservatives, with more than two-thirds of the votes and a majority of 8,858. He held the seat until his elevation to the peerage in 1965.

• Salisbury (UK Parliament constituency)
• Salisbury
• 1931 Salisbury by-election
• 1965 Salisbury by-election
• List of United Kingdom by-elections