Demetrios Vikelas (also Demetrius Bikelas; Greek: Δημήτριος Βικέλας; February 15, 1835 – July 20, 1908) was a Greek businessman and writer; he was the first president of the International Olympic Committee (IOC), from 1894 to 1896.

After a childhood spent in Greece and Constantinople (now Istanbul), he found fortune in London, where he married. He then moved to Paris, on account of his wife. Abandoning business, he dedicated himself to literature and history, and published numerous novels, short stories and essays, which earned him a distinguished reputation.

Because of his reputation and the fact that he lived in Paris, he was chosen to represent Greece in a congress called by Pierre de Coubertin in June 1894, which decided to re-establish the Olympic Games and to organise them in Athensin 1896, designating Vikelas to preside over the organisation committee. After the Games were over, he stepped down, remaining in Athens until his death in 1908.

Vikelas was born in Ermoupoli, on the island of Syros in Greece. His father was a merchant, originally from Veria (then under Ottoman rule, now in Macedonia) and his mother, Smaragda, was a member of the rich Melas family. He was educated at home by his mother, possibly due to his fragile health.

When he was six, the family moved to Constantinople, and ten years after that to Odessa. There he started working for his father's business.

Already he showed signs of his literary potential. At the age of 17 he translated Esther, a tragedy by Jean Racine.