Eustace, also rendered Eustis, ( ) is the rendition in English of two phonetically similar Greek given names: Εὔσταχυς (Eústachys) meaning "fruitful", "fecund"; literally "abundant in grain"; its Latin equivalents are Fæcundus/Fecundus Εὐστάθιος (Eustáthios) meaning "steadfast", "stable"; literally "possessing good stability"; its exact Latin equivalents are Constans and its derivatives, Constantius and Constantinus. Equivalents in other languages include Ostap (Ukrainian, Russian), Eustachy (Polish, Russian), Yevstaphiy (Russian), Eustachio (Italian), Eustache or Eustathe (French), Eustaquio (Spanish), Eustáquio (Portuguese), Eustàquio (Valencian), Ustes (Guyanese) and Eustice (English). The originally Hebrew name Ethan or Eitan can also mean "steadfast" or "stable". The Greek Eústachys is no longer used; Eustáthios/Ευστάθιος (usually transliterated Efstáthios) on the other hand is still popular and often used in the informal or diminutive Στάθης (Státhis). Notable people with the name Given name Ancient era Saint Eustace (died 118), Christian martyr Eustace or Eustathius of Mtskheta (died c. 550), Orthodox Christian saint Eustace of Luxeuil (Eustasius) (c. 560 – c. 629), saint and Abbot of Luxeuil Medieval era Eustace I of Boulogne (died 1049), father of Eustace II Eustace II of Boulogne (c. 1015–1020 – c. 1087), companion of William the Conqueror, fought at the Battle of Hastings Eustace III of Boulogne (before 1060 – c. 1125), rebelled against King William II of England, son of Eustace II Eustace IV of Boulogne (c. 1129 – 1153), eldest son of King Stephen of England Eustace (Bishop of Ely) (died 1215), Lord Chancellor of England Eustace de Balliol (died c. 1209), Lord of Balliol Eustace Chapuys (c. 1490/2 – 1556), Ambassador for the Holy Roman Empire in the English Court during the reign of Henry VIII Eustace of Fauconberg (died 1228), Bishop of London and Lord High Treasurer Eustace Folville (died 1346), English outlaw Eustace fitz John (died 1157), magnate in northern England Eustace Grenier (died 1123), crusader lord and Constable of the Kingdom of Jerusalem Eustace the Monk (c. 1170–1217), mercenary and pirate Eustace de Vesci (1169–1216), English lord of Alnwick Castle, leader of the First Baron's War against King John I of England Eustace of Vilnius (died 1347), saint and martyr of the Russian Orthodox Church Eustathius of Ethiopia (1273-1352), Ethiopian saint who advocated for Sabbath observance Modern era Eustace Akwei, Ghanaian doctor and politician Lord Eustace Cecil (1834–1921), British politician Eustace Conway, American naturalist Eustace John, Governor-General of Nevis Eustace Lycett (1914–2006), British special effects artist Eustace Miles (1868–1948), British real