He was best known for his historical films, such as Mihai Viteazul (1970, released in English both under the equivalent title Michael the Brave and also as The Last Crusade), Dacii (1966, Les Guerriers), Războiul Independenței (1977, War of Independence), as well as for his series of thrillers that take place in the interwar Kingdom of Romania, such as Un comisar acuză (1973, A Police Inspector Calls).

Joanna Pacuła starred in his film Ultima noapte de dragoste [ro] (The Last Night of Love) in 1980 before eventually emigrating to the United States, where he went on to a very successful career.

[2][3] Sergiu was born in Târgu Jiu, Gorj County, but grew up in Timișoara, where his family moved when he was 5 years old.

In his native Romania he is remembered as a superstar for his patriotism, the high praise he gained as a film director, and his charismatic and strong personality.

Nicolaescu's debut as a director was in 1962 with the short film Scoicile nu au vorbit niciodată (Shells Have Never Spoken).

[6] Mihai Viteazul (Michael the Brave) ruled the Romanian-speaking principalities (Wallachia, Moldavia, and Transylvania), a union he accomplished under his reign for a very brief period (1600–1601).

It was initially planned that Sergiu Nicolaescu would produce Mihai Viteazul with Hollywood superstars playing the lead characters.

The obstacle, eventually, was circumvented by means of casting, in the lead role of Mihai Viteazul the actor Amza Pellea, who achieved a masterful rendition of the hero.

Most of Nicolaescu's films are built around figures and events in Romanian history, and although showing superior mastery, in the (imposed) realistic approach they somewhat follow the patterns of historical movies from the Communist governed countries.

Nevertheless, Mircea was officially blocked from distribution, until the Romanian Revolution of 1989 ("All I've done was to present a different state leader than Nicolae Ceaușescu.

For instance, when making Mihai Viteazul, Nicolaescu successfully managed a 5,000-member crew, actors and extras and, despite the obvious technical limitations of the communication means in the 1970s (no mobile phones were available at that time, for instance), he imposed a strict discipline during filming of every cannon fire and every attack scene, thus helping everything to fall in place under his unique order.

While creating such historical movies he was supported by the Romanian Ministry of Defence with large numbers of extras and war equipment.

He documented his historical movies meticulously, to this end seeking the advice of military consultants and distinguished historians of the Romanian Academy.

It was a big merit of Sergiu Nicolaescu that, for all difficult or very risky tasks, he was able to show in detail to any actor or camera operator exactly what they had to do before they did it.

In such circumstances, during his 50 years career as film director and actor, Nicolaescu experienced several accidents or illness: still he went on performing and finished his movie projects with courage and sometimes at great personal cost (e.g., while producing Mihai Viteazul).

After Mircea, Nicolaescu expands on historical themes, directing films that shed positive light on Ion Antonescu, Romania's Axis-aligned dictator in the World War II period (his Începutul adevărului, also known as Oglinda), or glorified the World War I heroine Ecaterina Teodoroiu (Triunghiul morţii, also known as Triangle of Death).

When asked to nominate three movies he made that he most liked, Nicolaescu chose Mihai Viteazul (also known as Michael the Brave), Osînda (also known as The Doom) and Atunci i-am condamnat pe toți la moarte (also known as Then I Sentenced Them All to Death).

On 26 December 2012 he was admitted with atrial fibrillation and a traumatised thorax with pulmonary contusion to the Elias Hospital in Bucharest.