Vasilissa (300–309) was a Roman Christian girl who is venerated as a child martyr by the Russian Orthodox Church.
According to tradition, she was a small child when martyred, suffering in Nicomedia not long after the death of St. Anthimus.
The torturers covered her whole body with wounds, but she remained faithful to Jesus Christ.
According to Holy Tradition, she was tortured with fire and wild beasts, yet remained unharmed.
Vasilissa is said to have gone into a field, and fallen to her knees in prayer, thanking God for her endurance under torture, and whilst praying, she was martyred.