Ernst Moritz Theodor Ziller (; Greek: Ερνέστος Τσίλλερ, Ernestos Tsiller [ˈtsiler]; 22 June 1837 – 4 November 1923) was a German-born university teacher and architect who later became a Greek national. In the late 19th and early 20th centuries, he was a major designer of royal and municipal buildings in Athens, Patras, and other Greek cities.
Ziller was born in the rural community of Serkowitz in the district of Radebeul in the Kingdom of Saxony. After graduating from the Dresden Academy of Fine Arts in 1858, he went to work for Danish architect Theophilus Hansen. In 1861, Hansen sent him to Athens. In 1872 he was appointed a professor at the Royal School of Arts, now National Technical University of Athens.
He was married to a Greek wife, Sofia Doudou. His daughter Iosifina Dimas-Ziller (1885-1965) was an impressionist painter.
In 1885, he designed a three-story mansion where his family resided until 1912. Now known as the Ziller mansion, the residence was later acquired by Greek banker Dionysios P. Loverdos (1878–1934). Ziller died in Athens and was buried at the First Cemetery of Athens.
Below is a list of buildings designed by Ernst Ziller.
Andreas Syngros mansion (now Ministry of Foreign Affairs)
Hotels "Megas Alexandros" and "Bakeion", Omonoia Square
Iliou Melathron (now Numismatic Museum of Athens)
National Chemistry Institute of Greece (at the University of Athens)
Old building of the Hellenic Military Academy
Old headquarters building of the National Bank of Greece
Thon mansion (destroyed during the Dekemvriana)
Church of Agios Nikolaos Thon, the only surviving building from the Thon Estate
Loverdos Museum (former Ziller mansion, Academy Street 58a)
Transfiguration of Jesus church in Vilia, West Attica
Archaeological Museum of Aigion (old Municipal market)
Cathedral Church of Panagia Faneromeni
Parthenagogeio (Girls School) of Gytheio