Anthony, John, and Eustathius (Eustathios, Eustace; Russian: Антоний, Иоанн and Евстафий, Lithuanian: Antanas, Jonas ir Eustachijus; Martyrs of Vilnius, Russian: Виленские мученики, Lithuanian: Vilniaus kankiniai) are saints and martyrs (died 1347) of the Russian Orthodox Church. Their feast day is celebrated on April 14 in the horologion.

They were attached to the Grand Duchy of Moscow, and were missionaries dispatched to the court of Algirdas, who the pagan Grand Duke of Lithuania. Algirdas was wed to the Orthodox princess, Maria of Vitebsk, and the three were permitted to minister only to her and banned from proselytizing.

The youths were later arrested for preaching in public, and were ordered by Algirdas to consume meat in his presence during an Orthodox fasting period. When they refused, they were tortured and executed.

Their bodies were in a glass reliquary in the crypt chapel under the altar of the cathedral in the Monastery of the Holy Spirit in Vilnius, Lithuania. Their relics, said to be incorruptible, have since been moved to the main sanctuary of the cathedral.

They are also been recognised as saints in the Catholic Church, after having been added to the General Roman Calendar by Pope Paul VI in 1969.^[1]