Konstantinos Amantos (Greek: Κωνσταντίνος Άμαντος; 2 August 1874 – 23 January 1960) was a Greek Byzantinist and university professor.
Konstantinos Amantos was born on 2 August 1874 on Chios, then part of the Ottoman Empire. After completing school in Chios, he was appointed as a teacher at the island's "Civic School" (Ἀστικῆ Σχολῆ) in 1893. He remained at this post until 1897, when, through a scholarship granted from the bequest of the Chiot benefactor Stamatis Proïos, he was able to continue his studies. He studied first at the University of Athens, and in 1899 moved to the University of Munich, where he studied under the famous Byzantinist Karl Krumbacher. Amantos received his doctorate in 1903, with a treatise on the suffixes of modern Greek toponyms.
On his return to Greece, Amantos worked in 1904–1911 as professor at the Gymnasium of Chios, then as director of the Gymnasium of Nicosia (1911), and in 1912–1914 as director of the Ampeteios School at Cairo. In 1914, he was selected as an editor for the Historical Dictionary of the Greek Language (Ἰστορικὸν Λεξικὸν τῆς Ἑλληνικῆς Γλώσσης), a position he held until 1924, when he became director of the project. In 1925, he was elected to the chair of Byzantine history at the University of Athens, and held the post until his retirement in 1939. In 1926 he became a founding member of the Academy of Athens. In 1945 he served as Minister of Education in the short-lived cabinet of Nikolaos Plastiras (4 January – 8 April).
Amantos published several studies on linguistic issues, particularly of the dialect of his native Chios, as well as the historical geography of the Greek world. He was also active as the editor of the journals Chian Chronicles (Χιακά Χρονικά) and Aegean (Αἰγαῖον), which focused on Chios, as well as the journal Hellenica (Ἑλληνικά), which he published in 1928–1939 along with Dionysios Zakythinos and Sokratis Kougeas.