Laiou was born in Athens on 6 April 1941 to a Pontic family, refugees from the Black Sea coast of modern Turkey. She studied at the Athens College and continued her studies in the Philosophy School of the University of Athens (1958–59), where she studied under the Greek Byzantinist Dionysios Zakythinos, who awakened her interest in the Byzantine Empire. She moved to Brandeis University from where she graduated with her BA in 1961, and completed a post-graduate course and received her PhD from Harvard in 1966, under the supervision of Robert Lee Wolff, one of the leading historians of the Crusades. Her doctoral thesis became the basis for her first book, published in 1972 as Constantinople and the Latins: The Foreign Policy of Andronicus II, 1282–1328.
In 1962, she went to lecture at the University of Louisiana[disambiguation needed], before returning to Harvard, where she stayed from 1966 to 1972, first as instructor and then as assistant professor. She then moved to Brandeis, where she remained until 1981, becoming distinguished professor. During this period, she also taught at Rutgers College of Rutgers University. In 1981, she returned to Harvard to occupy the prestigious Dumbarton Oaks Professorship of Byzantine Studies, a post she held until her death. In 1985–88, she served as the head of Harvard's History Department—the first woman to head a department at Harvard—and from 1989 until 1998 she headed the distinguished Dumbarton Oaks Research Library and Collection in Washington, DC—again the first woman to do so.
With her Laiou pioneered the study of Byzantine and wider medieval society, and especially the role of women. Her article on The role of women in Byzantine society, published in the Jahrbuch der österreichischen Byzantinistik in 1981, "opened a new field for scholars of Byzantium". Her works on Peasant Society in the Late Byzantine Empire (1977) and Mariage, Amour et Parenté à Byzance Aux XIe-XIIIe Siècles (1992) were among the first studies in their field. During her last years, she presided over the compilation of the three-volume Economic History of Byzantium (2002), a definitive work in this until then rather neglected field, followed up a few years later by The Byzantine Economy (2007), her last book.
In her native Greece, she was honoured by being inducted into the Academy of Athens in 1998, only the second woman after the writer Galateia Saranti, and by being decorated with the Commander class of the Order of Honour. In the April 2000 elections, she was elected as a member of the Hellenic Parliament on the list of the Panhellenic Socialist Movement. In May 2000, she was also named as Deputy Secretary of Foreign Affairs charged with relations with the Greek diaspora. Disappointed with the realities of the job, she resigned the post six months later to resume her academic activities, and resigned her Parliament seat as well in 2002. Laiou was also a corresponding member of the Académie des Inscriptions et Belles-Lettres, the Austrian Academy of Sciences, a foreign member of the Serbian Academy of Sciences and Arts, a member of the Medieval Academy of America and of the American Academy of Arts and Sciences, and an honorary professor at Nankai University.
Diagnosed with thyroid cancer in September 2008, she died in Boston on 11 December 2008. She was married to Stavros Thomadakis, a former chairman of the Greek Capital Market Commission, whom she later divorced. She is survived by a son, Vassilis Thomadakis.
Major works 
|About Angeliki Laiou|
|By Angeliki Laiou|
- Laiou, Angeliki E. (1972), Constantinople and the Latins: The Foreign Policy of Andronicus II, 1282–1328, Harvard University Press, ISBN 674-16535-7 Check
- Laiou, Angeliki E. (1977), Peasant society in the late Byzantine Empire: a social and demographic study, Princeton University Press, ISBN 978-0-691-05252-6
- Laiou, Angeliki E.; Maguire, Henry, eds. (1992), Byzantium, a world civilization, Dumbarton Oaks Research Library and Collection, ISBN 978-0-88402-200-8
- Laiou, Angeliki E. (1992), Mariage, amour et parenté à Byzance aux XIe–XIIIe siècles (in French), Paris: De Boccard, ISBN 978-2-7018-0074-5
- Laiou, Angeliki E., ed. (1993), Consent and coercion to sex and marriage in ancient and medieval societies, Dumbarton Oaks Research Library and Collection, ISBN 978-0-88402-213-8
- Laiou, Angeliki E.; Simon, Dieter (1994), Law and society in Byzantium, 9th–12th centuries, Dumbarton Oaks, ISBN 978-0-88402-222-0
- Ahrweiler, Hélène; Laiou, Angeliki E. (1998), Studies on the Internal Diaspora of the Byzantine Empire, Washington, D.C.: Dumbarton Oaks Research Library and Collection, ISBN 0-88402-247-1
- May, Ernest R.; Laiou, Angeliki E. (1998), The Dumbarton Oaks conversations and the United Nations, 1944-1994, Dumbarton Oaks Research Library, ISBN 978-0-88402-255-8
- Laiou, Angeliki E.; Mottahedeh, Roy Parviz, eds. (2001), The Crusades from the Perspective of Byzantium and the Muslim World, Washington, D.C.: Dumbarton Oaks Research Library and Collection, ISBN 0-88402-277-3
- Laiou, Angeliki E., ed. (2002), The Economic History of Byzantium from the Seventh through the Fifteenth Century, Dumbarton Oaks Research Library and Collection, ISBN 0-88402-288-9
- Laiou, Angeliki E., ed. (2005), Urbs capta: the Fourth Crusade and its consequences, Lethielleux, ISBN [[Special:BookSources/978-2-283-60464-8|978-2-283-60464-8 [[Category:Articles with invalid ISBNs]]]] Check
- Laiou, Angeliki E.; Morrison, Cécile (2007), The Byzantine Economy, Cambridge, UK: Cambridge University Press, ISBN 0-521-84978-0
- "Professor Angeliki Laiou: expert on women in the Byzantine empire". The Times. 17 December 2008. Retrieved 12 November 2010.
- Cécile Morrisson (26 March 2009). "Angeliki Laiou: Influential and highly regarded scholar of Byzantium". The Independent. Retrieved 12 November 2010.
- "ΑΓΓΕΛΙΚΗ ΛΑΪΟΥ (1941-2008): Μια σπουδαία γυναίκα, μια πραγματική «δασκάλα»" (in Greek). 15 December 2008. Retrieved 12 November 2010.
- "Professor Angeliki Laiou dies of cancer". Harvard History Department News. 15 December 2008. Retrieved 12 November 2010.