Brigadier Sir Alexander Beville Gibbons Stanier, 2nd Baronet of Peplow Hall, DSO & Bar, MC (31 January 1899 – 10 January 1995) was a British Army officer who fought in the First and Second World Wars, particularly distinguished for his actions at Boulogne in 1940, on D-Day in 1944, and in the Rhineland in 1944.

Stanier was born on 31 January 1899, the eldest son of Beville Stanier of Peplow Hall in Shropshire. His father was elected Member of Parliament for Newport, Shropshire, in 1908, and was created a Baronet by David Lloyd George in 1917 for organising Sugar beet production during the First World War. In that year, his son Alexander, who had been educated at Summer Fields and Eton, passed through the Royal Military College at Sandhurst as a wartime cadet and was commissioned into the newly raised Welsh Guards on 21 December.

In his year with the 1st Battalion of the Welsh Guards on the Western Front, Stanier displayed aptitude for the mobile warfare that followed the crumbling of the German defences. He was awarded the Military Cross (MC) (dated 2 April 1919) for his actions during the Second Battle of Cambrai, a month before the Armistice. His citation reads as follows:

For conspicuous gallantry and able leadership at St. Vaast on 11 October 1918. He rallied his platoon under heavy fire, and after personally reconnoiting (sic) the ground in front, led his men forward 200 yards to a good fir[ing] position. His good leadership and prompt action prevented casualties and gained valuable ground.

Stanier decided to pursue a military career when the war ended, and he continued in the Army rather than manage the family estates when his father died in 1921 and he succeeded to the baronetcy as Sir Alexander Stanier. He was promoted to lieutenant on 21 June 1919. He served with the 1st Battalion, Welsh Guards in Germany, Egypt and Gibraltar, being the battalion adjutant in 1923–26, with a promotion to captain on 1 October 1924. From 1927 to 1930 he was military secretary to the governor of Gibraltar, successively serving General Sir Charles Monro and General Sir Alexander Godley.

He relinquished this assignment in January 1930 and was promoted to major on 1 October 1932 and to lieutenant-colonel on 18 May 1939.

On the outbreak of the Second World War, Stanier was given the task of raising a second Battalion of the Welsh Guards. In May 1940, when it became clear that the Battle of France was lost and that the British Expeditionary Force would have to be evacuated, 2nd Welsh Guards and 2nd Irish Guards were hastily sent (as 20th Independent Infantry Brigade) to Boulogne to cover the withdrawal of British troops through that port. This was a hazardous operation and could easily have led to the destruction or capture of the force, but Stanier made his dispositions soundly, and although badly mauled his battalion was successfully evacuated by the Royal Navy while destroyers engaged German tanks on the quay. Stanier was awarded his first Distinguished Service Order for his bravery and leadership during this two-day operation.

Stanier was given the temporary rank of brigadier and assigned command of a new home defence brigade, the 223rd Independent Infantry Brigade, which he commanded and trained from its formation on 18 October 1940 until it was converted into the 3rd Parachute Brigade on 7 November 1942. He continued in command during the conversion period until 8 December, when he handed over to Brigadier Gerald Lathbury.