The Szécsényi was a noble family of the Kingdom of Hungary in the 14-15th centuries. The ancestor of the family, Thomas descended from the gens ("clan") Kacsics. He was one of the most powerful barons of King Charles I of Hungary and he hold several dignities during his reign. The family was named after its possession, Szécsény. The male line of the family ended in 1460.
Thomas Szécsényi (cca. 1285-1354), the son of Farkas Szécsényi, joined King Charles I against the powerful Máté Csák in 1301; therefore, his relatives who followed Máté Csák occupied his inherited possessions in Nógrád county. He fought at the Battle of Rozgony/Rozhanovce (15 June 1312) when the king's armies defeated the allied troops of Máté Csák and Amade Aba's sons. Shortly afterwards, the king granted Thomas the possession of Hollókő that had been confiscated from his relatives. In 1316, he occupied the Visegrád Castle from Máté Csák. He became the head (ispán) of Arad, Bács and Szerém counties (1318) and the Magistrate of the Cumans (1319). In 1320, he was appointed to the Master of the Queen's Treasury (királynéi tárnokmester). Around that time, he married one of Queen Elisabeth's relatives, Anna of Oświęcim as his second wife. Following Máté Csák's death (1321), the king granted him several castles and possessions in Heves, Gömör and Nógrád counties; thus, he received Ajnácskő (today Hajnáčka in Slovakia) , Baglyaskő, Bene, Somoskő (today Šomoška in Slovakia) and Sztrahora Castles. In the same year, he became the Voivode of Transylvania. He suppressed the rebellion of the Transylvanian Saxons (1324) and the king granted him Salgó Castle (today Sibiel in Romania). In 1342, he was appointed to the office of Master of the King's Treasury (tárnokmester) and in 1349, he became the High Justiciar of the Kingdom (országbíró).