EUSTATHIUS, a famous Græco-Roman jurist, who flourished at Constantinople in the latter half of the tenth century, and filled various high offices under the emperors who reigned during that period. He is frequently mentioned under the names of Patricius, Magister, and Romanus. Besides his Romæa, frequently quoted by later jurists, Eustathius wrote a number of other works never published, the MSS. of which are still extant in the Vatican at Rome, in Paris, and elsewhere.