Prince Nicholas of Romania (Romanian: Principele Nicolae al României; 5 August 1903 – 9 June 1978), later known as Prince Nicholas of Hohenzollern-Sigmaringen, was the fourth child and second son of King Ferdinand I of Romania and his wife Queen Marie.

In 1927 after the death of his father, Nicholas was appointed as one of the three regents for his minor nephew King Michael I. His position as regent ended in 1930 with the return of his older brother Prince Carol to Romania to take over as King of Romania.

In later 1930, he was stripped of his titles and privileges and exiled from the Royal Court, due to King Carol II's disapproval of his marriage. On 10 July 1942, after the removal of King Carol II from the throne, during King Michael's second reign, Nicholas was given by the king the title of Nicholas of Hohenzollern — of the house to which he belonged.

He died in exile on 9 July 1978 in Madrid, Spain.

Nicholas was born on 5 August 1903 in Peleș Castle, Sinaia as the second son of Crown Prince Ferdinand of Romania and his wife Princess Marie of Saxe-Coburg and Gotha and Edinburgh. His siblings were Carol II of Romania, Elisabeth of Romania, Queen Maria of Yugoslavia, Princess Ileana of Romania and Prince Mircea of Romania. Nicholas was named after his mother’s first cousin, Nicholas II, the last Emperor of Russia.

In her memoirs, his mother wrote: "He was exceedingly independent, and always funny. He never could be still for a second; he was for ever “up and doing.” Although far from good or obedient, he had a way of getting people to do what he wanted. Wherever Nicky went, he went to rule and order about, not because he was imperious and aggressive, but because he was funny. His funniness was of the good-humoured, irresistible kind which amuses even the dullest. Even as a tiny tot, his repartees were so comic that, instead of receiving the scolding he deserved he roused instead fun and laughter. Comically sly, he always had his own way, breaking down every defence or restriction." He had a long nose, piercing blue eyes and silvery hair. His mother recalled him often tugging his sister Mignon's hair.

Nicholas was the younger brother of Carol, heir apparent, who renounced his rights of succession on 12 December 1925. When Ferdinand died in 1927, he was succeeded as King by Carol's five-year-old son, Michael; Nicholas himself had been proposed as heir-apparent when Carol married the commoner Zizi Lambrino in 1918 (a marriage later annulled). Given Michael's youth, a regency council had to be formed (20 July), and Prince Nicholas was forced to abandon his career in the British Royal Navy—in which he held the honorary rank of sub-lieutenant—in order to return home to serve on the council, alongside Gheorghe Buzdugan and Patriarch Miron Cristea.

Although unofficially referred to as "the first-ranking regent", Nicholas resented having to abandon his naval career and had no interest in politics. He tried to continue his father's cooperation with the National Liberals (PNL), and to contain the opposition of the National Peasants' Party (PNŢ) to the regency by appointing a national government under Ion I. C. Brătianu. Refused by Brătianu, he witnessed a change in Carol's stance in mid-1927, when the latter argued that he had been forced to give up his throne. The cooperation between Carol and the PNŢ was successfully neutralized by the PNL, but Brătianu's death in 1927 restored contacts and increased the appeal of the PNŢ. By then, the regency was widely perceived as consisting of figureheads, and, after Constantin Sărăţeanu (an appointee of PNŢ leader Iuliu Maniu) succeeded the deceased Buzdugan in 1929, it was believed to be torn apart by contrasting political ambitions. According to Nicolae Iorga, Miron Cristea himself had said:^{[citation needed]}