Theodoros G. Orphanides (also appears as Theodoros G. Orphanidis, Greek: Θεόδωρος Ορφανίδης) (born 1817 - died 5 August 1886 in Athens) was Professor of Botany at the National and Kapodistrian University of Athens, and one of the leading representatives of the First Athenian School. He recheived three times the Ralio award.
He was born at Izmir but his parents were from Chios, Greece. His older brother was Dimitris Orphanides that became Professor of Medicine. After the outburst of the Greek Revolution, his family was forced to move first to Nafplio and later at Tinos and Syros island where he finish with his high school studies. At 1835 he moved to Athens where he was appointed as Ministerial Scribe at the Ministry of Interior while he started writing political satire. However, because he was criticizing against the Bavarian regency with his writings, he was fired from the Ministry and was sentenced to jail for 3 days. At 1844 after personal intervention of the Greek Prime Minister, Ioannis Kolettis, which he wanted to oust him from Athens, he attended a Governmental scholarship to study Botany at Paris close to Adrien-Henri de Jussieu, Adolphe-Théodore Brongniart, Joseph Decaisne and Achille Richard.
When he returned to Athens on 11 August 1850 he was appointed as Extraordinary Professor of Botany at the National and Kapodistrian University of Athens, while in 1854 he became Full Professor, a position that he kept for over thirty years. Between the years 1867 – 1868 Orphanides was Rector of the University. He was a tireless delver of the Greek flora, collecting and recording several species. His plant material formed a remarkable Herbarium (over 45,000 specimens) which after his death was bought by the national benefactor Theodoros Rodokanakis, where later on it was given to the Botanical Museum of the University. He traveled across Greece studying systematically the Greek plant diversity and he published his findings at his work "Flora Graeca Exciccata". His studies that were exploited from other European researchers, established him in his scientific areas. As a Superintendent of the Botanical Garden and the State Arboretum, he introduced in Greece, unknown until then, ornamental plants and he was actively involved in the design and creation of urban public parks, overriding the creation of the National Garden, Athens. Theodoros Orphanidis was friend and collaborator of Theodor von Heldreich and Pierre Edmond Boissier.
The plant species Heracleum orphanidis, Centaurea orphanidea, Biebersteinia orphanidis, Campanula orphanidea, Euphorbia orphanidis, Nepeta orphanidea, Tulipa orphanidea, Verbascum orphanideum and Viola orphanidis are named after him.