Horacio Verbitsky (born February 11, 1942) is an Argentine investigative journalist and author with a history as a leftist guerrilla in the Montoneros. In the early 1990s, he reported on a series corruption scandals in the administration of President Carlos Menem, which eventually led to the resignations or firings of many of Menem's ministers. In 1994, he reported on the confessions of naval officer Adolfo Scilingo, documenting torture and executions by the Argentine military during the 1976–1983 Dirty War. His books on both the Menem administration and the Scilingo confessions became national bestsellers. As of January 2015 Verbitsky is a Commissioner for the International Commission against the Death Penalty.

Verbitsky become immersed in controversy following the election of Cardinal Jorge Mario Bergoglio as Pope Francis, due to Verbitsky's accusations that Bergoglio was complicit with military dictators during the so-called Dirty War. These claims have been disputed. The Argentine journalist Gabriel Levinas and his investigative team in early September 2015 came out with the best-selling book, Doble Agente. La biografía inesperada de Horacio Verbitsky (Double Agent: The unexpected biography of Horacio Verbitsky), documenting Verbitsky's work with the Argentine military during the period of state terror. September 2016, former Argentine Army chief César Milani, a frequent Verbitsky target on alleged human rights grounds, responded bluntly that his critic "has to explain his time during military dictatorship," adding, "His friends were senior military officials. Why was it that he never questioned them?"

Verbitsky heads the Center for Legal and Social Studies (CELS), an Argentine human-rights organization. During the COVID-19 pandemic in Argentina, CELS distanced itself from Verbitsky after his involvement in a scandal in which Verbitsky used his connection with the former Minister of Health Ginés González García to receive the COVID-19 vaccine, at that time multiple front-line doctors were not yet inoculated. For this episode, the president Alberto Fernández, requested the resignation of González García, who was quickly replaced by Carla Vizzotti.

Verbitsky was born in Buenos Aires in 1942 and he is the son of the also Argentine journalist and writer Bernardo Verbitsky. His paternal grandparents were Ukrainian-Jewish immigrants. Since 1960, he has earned national acclaim for his writings and political columns, focusing primarily on the unmasking of political corruption and the promotion of a free press, denouncing any government policies that may affect the constitutional rights of free speech for journalists and citizens. He has also become known by the nickname "el Perro" ("the dog"), for his determination in uncovering stories.

During the 1970s he was a member of Montoneros, a Peronist guerrilla organization that was engaged in terrorist activities in Argentina. According to him, he participated in shootings, during which "luckily" nobody died. He also stated that he had no important functions in the Montoneros organization, although former Montoneros commanders Juan Zverko, Rodolfo Galimberti and Carlos Patané have claimed otherwise. and point him out as the person that detonated a powerful bomb at the parking lot of the Argentine Army Headquarters by remote control on 15 March 1976, that wounded 15 military servicemen and 6 civilians as well as killing a civilian passerby.

Along with Mario Firmenich and five other Montoneros, he was indicted for allegedly being involved in the planning and execution of the bombing of the Superintendence of Security of the Federal Police, on July 2, 1976 — a few months after the military coup — which caused 21 deaths mainly among NCOs and 100 wounded. The case was however closed in 2007 because of statute of limitations.

"I have been a Peronist since I was 13 years old. I have been a journalist since I was 18 years old. I have been a Peronist militant since I was 19 years old. I stopped being a Peronist in 1973 and I stopped being a Montonero in 1977. I am still a journalist."

— Horacio Verbitsky, interviewed by the weekly magazine La Maga