Catholic University of Leuven (1834\u20131968) alumni

Georges Henri Joseph Édouard Lemaître ( lə-MET-rə; French: [ʒɔʁʒ ləmɛːtʁ] ; 17 July 1894 – 20 June 1966) was a Belgian Catholic priest, theoretical physicist, mathematician, astronomer, and professor of physics at the Catholic University of Louvain. He was the first to theorize that the recession of nearby galaxies can be explained by an expanding universe, which was observationally confirmed soon afterwards by Edwin Hubble. He first derived "Hubble's law", now called the Hubble–Lemaître law by the IAU, and published the first estimation of the Hubble constant in 1927, two years before Hubble's article. Lemaître also proposed the "Big Bang theory" of the origin of the universe, calling it the "hypothesis of the primeval atom", and later calling it "the beginning of the world".

Léo Pétillon (22 May 1903 – 1 April 1996) was a Belgian colonial civil servant and lawyer who served as Governor-General of the Belgian Congo (1952–58) and, briefly, as Minister of the Belgian Congo and Ruanda-Urundi (1958).
Pétillon studied Law and practiced as a lawyer, before entering the Belgian colonial service in 1929. He worked for several years at the Ministry of the Colonies in Brussels, serving as aide to a series of ministers. In 1939, he secured a posting to the Belgian Congo as aide to the Governor-General and spent most of World War II in the colony or with the Belgian government in exile in London. In 1946, Pétillon was promoted to Vice Governor-General, given responsibility for the Belgian mandate of Ruanda-Urundi. In 1952, he was promoted to the position of Governor-General himself, holding the position until 1958. After the end of his tenure, he briefly held a Ministerial position himself as technocrat in the government of Gaston Eyskens. He retired in 1959 and published several books. He died in 1996.

Raymond Martin Marie Ghislain, Baron Lemaire (Uccle, 28 May 1921 - Woluwe-Saint-Lambert, 13 August 1997) was an art historian and an architectural historian, a leading expert in conservation and professor at the Catholic University of Leuven and later at the KU Leuven and the Université catholique de Louvain in Louvain-la-Neuve.

Charles-Jean Étienne Gustave Nicolas, baron de la Vallée Poussin (French pronunciation: [ʃaʁl ʒɑ̃ etjɛn ɡystav nikɔla baʁɔ̃ də la vale pusɛ̃]; 14 August 1866 – 2 March 1962) was a Belgian mathematician. He is best known for proving the prime number theorem.
The King of Belgium ennobled him with the title of baron.

Theophile Meerschaert (24 August 1847 – 21 February 1924) was a Belgian-born prelate of the Catholic Church. He served as the Bishop of the Diocese of Oklahoma (and its predecessor) in the United States from 1891 until his death in 1924.

Paul Adriaan Jan, Baron Janssen (12 September 1926 – 11 November 2003) was a Belgian physician. He was the founder of Janssen Pharmaceutica, a pharmaceutical company with over 20,000 employees which is now a subsidiary of Johnson & Johnson.

Émile Adolphe Gustave Verhaeren (Dutch: [vərˈɦaːrən]; 21 May 1855 – 27 November 1916) was a Belgian poet and art critic who wrote in the French language. He was one of the founders of the school of Symbolism and was nominated for the Nobel Prize in Literature on six occasions.