General Sir John Ormsby Vandeleur (1763 – 10 December 1849) was a British Army officer who fought in the French Revolutionary and Napoleonic wars.

The Vandeleurs, of Dutch origin, came to Ireland in the seventeenth century, and settled at Kilrush, County Clare, where they became the principal landowners.

On the embarkation of the British army for England in April 1795, Vandeleur remained with a small corps under General Dundas until December.

[1] In October 1802 Vandeleur went with his regiment to India, and served as lieutenant-colonel with the local rank of colonel in command of a brigade of cavalry under Lord Lake in the Second Anglo-Maratha War 1803–1805.

At the Battle of Laswari on 1 November 1803, Vandeleur turned the enemy's left flank and took two thousand prisoners, receiving the thanks of Lord Lake.

In June of the following year, he intercepted a French division and cut off one of its brigades, taking three hundred prisoners and forcing the remainder to disperse in the mountains.