In general, the term White Terror refers to acts of violence carried out by reactionary (usually monarchist or conservative) groups as part of a counter-revolution. In particular, during the 20th century, in several countries the term White Terror was applied to acts of violence against real or suspected socialists and communists.
The original White Terror took place in 1794, during the turbulent times surrounding the French Revolution. It was organized by reactionary "Chouan" royalist forces in the aftermath of the Reign of Terror, and was targeted at the radical Jacobins and anyone suspected of supporting them. Throughout France, both real and suspected Jacobins were attacked and often murdered. Just like during the Reign of Terror, trials were held with little regard for due process. In other cases, gangs of youths who had aristocratic connections roamed the streets beating known Jacobins. These "bands of Jesus" dragged suspected terrorists from prisons and murdered them much as alleged royalists had been murdered during the September Massacres of 1792.
Again, in 1815, following the return of King Louis XVIII of France to power, people suspected of having ties with the governments of the French Revolution or of Napoleon suffered arrest and execution. Marshal Brune was killed in Avignon, and General Jean-Pierre Ramel was assassinated in Toulouse. These actions struck fear in the population, dissuading Jacobin and Bonapartist electors (48,000 on 72,000 total permitted by the census suffrage) to vote for the ultras. Of 402 members, the first Chamber of the Restoration was composed of 350 ultra-royalists; the king himself thus named it the Chambre introuvable ("the Unobtainable Chamber"). The Chamber voted oppressive laws, sentencing to death Marshal Ney and general la Bédoyère, while 250 people were given prison sentences and some others exiled (Joseph Fouché, Lazare Carnot, Cambacérès).
The White Terror (Bulgarian: Бял терор, Byal teror) in Bulgaria occurred during the right-wing government of Aleksandar Tsankov (1923-1926). The Bulgarian Communist Party was repressed and martial law was declared. In 1925, after the Sofia bomb attack aimed to assassinate Tsar Boris III, the Communist Party was outlawed and persecution escalated, with many notable figures who had expressed Communist beliefs—for example, writer Geo Milev—being repressed, and many killed without trial. An estimated 5000 people perished in the Tsankovite White Terror.
On April 12, 1927, Chiang carried out purge of Communists from the Kuomintang in Shanghai and began large-scale killings. Chiang's forces turned machine guns on 100,000 workers taking to streets, killing more than 5000 people. Throughout April 1927 in Shanghai, more than 12,000 people were killed. The killing in Shanghai drove most of the Communists out of the urban cities and into the rural countryside.
The greatest slaughter took place in the countryside, however. The White Terror in China took millions of lives, most of them in the rural areas. The Chinese Communist Party was virtually extinguished. At the beginning of 1927, the Chinese Communist Party had about 60,000 members. By the end of the year, no more than 10,000 remained.
In February 1977, the EPRP initiated terrorist attacks - known as the White Terror - against Derg members and their supporters. This violence immediately claimed at least eight Derg members, plus numerous Derg supporters, and soon provoked a government counteraction - the Red Terror (Ethiopia).
After the Finnish Civil War of 1918, the victorious White troops of Carl Gustaf Mannerheim carried out terror against workers and suspected leftists. According to Finnish studies, some 80,000 people and their families were sent to concentration camps, where more than 11,783 died of disease or starvation. About 8500 people were executed. In Helsinki, the White Guards made workers' wives and children walk in front of their troops as they recaptured the city street by street. In Lahti, in one day, some 200 women were shot with explosive bullets. In Viipuri, 600 Red Guards were lined up in three rows and machine gunned to death.
In the aftermath of the World War I, Germany tottered on the brink of chaos. In an attempt to suppress the revolution, militias formed out of demobilized World War I veterans. The Freikorps, as they were called, were meant as a replacement for the Kaiser's Army, which had evaporated overnight due to desertion. The Freikorps was sent to suppress the revolution on the streets of Berlin and later invaded the Bavarian Soviet Republic. A large number of people were murdered in the subsequent terror. The number of workers who died in the repression of revolutionary developments in Germany from 1918 to 1921 was estimated at 15,000.
During 1945-1946, right-wing gangs killed about 1,190 pro-communist and left-wing civilians, and tortured many others. Entire villages that helped the partisans were attacked by those gangs.
One of the first such White Terrors outside Russia was the Hungarian White Terror, carried out by irregular and semi-regular detachments in Hungary in 1919-1920, after the fall of the Hungarian Soviet Republic in response to the Red Terror. Most of them formally belonged to Miklós Horthy's "National Army", but they were not under direct control, and disputed if Horthy had been known about their actions. Militias massacred approximately 600-2000 people, mostly communist Jews and alleged traitors.
The White Armies, foreign forces, and other opponents of the Soviet Government carried out mass violence against the population, tortured and shot people suspected of being associated with the soviets, destroyed villages, and tormented Red Army prisoners. After each town was captured, there was a protracted massacre of suspected opponents. Historians emphasize the fact the White terror was premeditated and systematic, as orders for terror came from high officials in the White movement, as well as legislative actions of the White regimes..
Some historians trace White Terror to 28 October 1917, when Moscow cadets captured revolutionary soldiers of the 56th Reserve Regiment, ordered them to line up ostensibly to check the Alexander II monument, and then proceeded to open fire with machine guns and rifles on unarmed people. More than 300 people were killed. .
White Guard leader Lavr Kornilov promised, "the greater the terror, the greater our victories." He vowed that the goals of his forces must be fulfilled even if it was needed "to set fire to half the country and shed the blood of three-fourths of all Russians." An order issued by Krasnov stated: "It is forbidden to arrest workers. The orders are to hang or shoot them." Another order issued by Kaledin said: "The orders are to hang all arrested workers in the street. The bodies are to be exhibited for three days." 
In eastern Russia and Siberia, terror was practiced. There was a massacre at a munitions factory in Samara carried out by the SR-Menshevik regime with the support of the Czechoslovak interventionists. More than 1,500 men, women, and children were killed with sabres. The total number of victims of the Czechoslovak interventionists in the summer and autumn of 1918 in the Volga region numbered over 5000 people. According to one historian, their cruelty often knew no bounds. Near Samara, following the suppression of peasant uprisings, more than 500 people were executed. In Simbirsk, about 400 people were shot. In Kazan, more than a thousand were executed. 
In Ekaterinburg region alone, more than 25,000 people were shot or tortured to death by Kolchak's forces. In March 1919 Admiral Kolchak himself demanded one of his generals to "follow the example of the Japanese who, in the Amur region, had decimated the local population." Kolchak's regime also used mass floggings, especially with rods. Kolchak issued orders to raze to the ground whole villages. In a few Siberian provinces, 20,000 farms were destroyed and over 10,000 peasant houses burned down. Kolchak's regime destroyed bridges and blew up water stations.
The Semenov regime in in Transbaikalia was characterized by mass terror and executions. At the Adrianovki station in summer of 1919, more than 1600 people were shot. 11 permanent death houses were set up, where refined forms of torture were practiced. Semenov himself admitted in court that his troops burned villages. Semenov persronally was in charge of his torture chambers, during which thousands of people were killed. Companion of Ataman Semenov, Major General Vlasyevsky testified in August 1945:
"White Cossack units of Semenyov brought much misery to the population. They shot people suspected of anything, burned villages, looted the population. Especially distinguished in this were teh forces of General Ungern. The greatest atrocities were committed by the death squads led by military chiefs like Filshin, Chistokin, and others who were aligned with Semenov.
In Orenburg, under attack by Ataman Dutov's Cossacks, there was widespread terror. According to an order of August 4, 1918, Ataman Dutov imposed on his territory the death penalty for the slightest resistance to authorities, as well as military draft evasion. In only one Ural district in January 1919, Dutov's Cossacks killed 1050 people. On April 3, 1919, those who showed the slightest sign of disloyalty were ordered to be shot. In the village of Sugar Dutov's men had burned the hospital, along with 700 people sick with typhus. .
In 1918 alone, the White guard regime in the Northern territory with a population of about 400 thousand, more than 38 thousand people were put in Archangel prisoners, of whom about 8 thousand were killed outright and thousands more succumbed to beatings and disease. 
In the occupied territories of southern Russia, White Guard regimes carried out mass executions and plunder. Bands of Kornilov’s officers left behind more than 500 dead in a Don village in early 1918. The press of the Denikin regime regularly incited violence against Jews. For example, a proclamation by one of Denikin's generals incited people to "arm themselves" in order to extirpate "the evil force which lives in the hearts of Jew-communists." In the small town of Fastov alone, Denikin's Volunteer Army murdered over 1500 Jews, mostly elderly, women, and children. An estimated 100,000 Jews in Ukraine were killed in pogroms perpetrated by Denikin's forces and Petlyura's nationalist-separatists. Hundreds of thousands of Jews were left homeless and tens of thousands became victims of serious illness. In the Don Province, where power was held by Krasnov's White Cossack regime, more than 45,000 people were shot or hanged. In one particular incident on 10 May 1918, the White Cossacks shot 78 men and hanged chairman of the Don Soviet Republic F. Podtelkov and secretary of the Don Military Revolutionary Committee M. Krovhoshlykov.
Before and during the Korean War, there were a series of reprisal killings carried out by South Korean security forces against suspected communists. The most infamous incident of this type occurred during the Jeju Uprising in the extreme south of the country.
During and after the civil war in Spain the Nationalist side executed an estimated 200,000 people.
Rooted in the anti-Communist White Terror on the Chinese Mainland and the 228 Incident or the 228 massacre on Taiwan in 1947, the "White Terror" describes the suppression of political dissidents and public discussion of the 228 Incident under the martial law period from May 19, 1949 to July 15, 1987.
In Russia, Ukraine, Belarus, and elsewhere, there are a significant number of monuments dedicated to victims of White Terror. Most monuments were planced on the mass graves of the terror. 
In the central square in Volgograd since 1920 there is a "Square of Fallen Fighters", where the remains of 55 victims of white terror are buried. A monument established in 1957 in black and red cranite has an inscription: "To the freedom fighters of Red Tsaritsyn. Buried here are the heroic defenders of Red Tsaritsyn brutally tortured by White Guard butchers in 1919."
A monument to victims of White Terror in Vyborg was made in 1961 near the Leningrad highway. It is dedicated to the victims of 600 prisoners shot by machine gun by the White Guards on the ramparts of the city. 
The "In Memory of Victims of White Terror" monument in Voronezh is located in a park near the regional Nikitinskaia libraries. The monument was unveiled in 1920 on the site of public executions in 1919 by the troops of Mamantov.
In Sevastopol on the 15th Bastion Street of December 1920, there is a "Communard Cemetery and victims of white terror". The cemetery is named in honor of the members of the Communist underground, murdered by Whites in 1919-20. 
In the city of Slavgorad in Altai, there is a monument for participants of the Chernodolsky Uprising and their families who who fell victim to the white terror of Ataman Annekov.