The 1st SS Panzer Division Leibstandarte SS Adolf Hitler or SS Division Leibstandarte, abbreviated as LSSAH (German: 1. SS-Panzerdivision "Leibstandarte SS Adolf Hitler"), was a Waffen-SS Panzer division that served from 1933 until it was disbanded in 1945. It began as Adolf Hitler's personal bodyguard unit, responsible for guarding the Führer's person, offices, and residences. Initially the size of a regiment, the LSSAH eventually grew into a division-sized unit during World War II.

The LSSAH participated in combat during the invasion of Poland and was amalgamated into the Waffen-SS together with the SS-Verfügungstruppe (SS-VT) and the combat units of the SS-Totenkopfverbände (SS-TV) prior to Operation Barbarossa in 1941. By mid-1942 it had been increased in size from a regiment to a Panzergrenadier division and was designated SS Panzergrenadier Division "Leibstandarte SS Adolf Hitler". It received its final form as a Panzer division in October 1943.

Members of the LSSAH perpetrated numerous atrocities and war crimes, including the Malmedy massacre. They killed an estimated 5,000 prisoners of war in the period 1940–1945, mostly on the Eastern Front.

In the early days of the Nazi Party, the leadership realized that a bodyguard unit composed of reliable men was needed. Ernst Röhm formed a guard formation from the 19.Granatwerfer-Kompanie ("19th Grenade Thrower Company"); from this formation the Sturmabteilung (SA) soon evolved. Adolf Hitler in early 1923, ordered the formation of a small separate bodyguard dedicated to his service rather than "a suspect mass", such as the SA. Originally the unit was composed of only eight men, commanded by Julius Schreck and Joseph Berchtold. It was designated the Stabswache (staff guard). The Stabswache were issued unique badges, but at this point was still under SA control. Schreck resurrected the use of the Totenkopf ("death's head") as the unit's insignia, a symbol various elite forces had used in the past, including specialized assault troops of Imperial Germany in World War I who used Hutier infiltration tactics.

In May 1923, the unit was renamed Stoßtrupp (Shock Troop)–Hitler. The unit numbered no more than 20 members at that time. On 9 November 1923, the Stoßtrupp, along with the SA and several other Nazi paramilitary units, took part in the abortive Beer Hall Putsch in Munich. In the aftermath, Hitler was imprisoned and his party and all associated formations, including the Stoßtrupp, were disbanded.

In the mid-1920s, violence remained a large part of Bavarian politics. Hitler was a potential target. In 1925, Hitler ordered the formation of a new bodyguard unit, the Schutzkommando (protection command). The unit was renamed the Sturmstaffel (assault squadron) and in November was renamed the Schutzstaffel, abbreviated to SS. By 1933 the SS had grown from a small bodyguard unit to a formation of over 50,000 men. The decision was made to form a new bodyguard unit, again called the Stabswache, which was mostly made up of men from the 1st SS-Standarte. By 1933 this unit was placed under the command of Sepp Dietrich, who selected 117 men to form the SS-Stabswache Berlin on 17 March 1933. The unit replaced the army guards at the Reich Chancellery. Out of this initial group, three eventually became divisional commanders, at least eight would become regimental commanders, fifteen became battalion commanders, and over thirty became company commanders in the Waffen-SS. Eleven men from the first company of 117 went on to win the Knights Cross, and forty of them were awarded the German Cross in gold for bravery. Later in 1933, two further training units were formed: ''SS-Sonderkommando Zossen on 10 May, and a second unit, designated SS-Sonderkommando Jüterbog on 8 July. These were the only SS units to receive military training at that time. Most of the training staff came from the ranks of the army. On 3 September 1933 the two Sonderkommando merged into the SS-Sonderkommando Berlin under Dietrich's command. Most of their duties involved providing outer security for Hitler at his residences, public appearances and guard duty at the Reich Chancellery.

In November 1933, on the 10th anniversary of the Beer Hall Putsch, the Sonderkommando took part in the rally and memorial service for the Nazi Party members who had been killed during the putsch. During the ceremony, the members of the Sonderkommando swore personal allegiance to Hitler. At the conclusion the unit received the new title, "Leibstandarte Adolf Hitler" (LAH). The term Leibstandarte was derived partly from Leibgarde – a somewhat archaic German translation of "Guard of Corps" or personal bodyguard of a military leader (Leib, lit. 'body, torso') – and Standarte: the Schutzstaffel (SS) or Sturmabteilung (SA) term for a regiment-sized unit, also the German word for a specific type of heraldic flag (Standard).

On 13 April 1934, Heinrich Himmler, head of the SS, ordered the Leibstandarte Adolf Hitler (LAH) to be renamed "Leibstandarte SS Adolf Hitler" (LSSAH). Himmler inserted the SS initials into the name to make it clear that the unit was independent from the SA or the army. The LSSAH was designated a "National Socialist" unit, which eventually grew into an elite Panzer Division of the Waffen-SS. Although nominally under Himmler, Dietrich was the real commander and handled day-to-day administration.