| Honorific Prefix: | Saint |
| Vasilissa Василисса Никомидийская Vasilissa of Nicomedia | |
| Birth Date: | 300 |
| Death Date: | 309 |
| Feast Day: | September 16 |
| Venerated In: | Russian Orthodox Church Roman Catholic Church |
| Death Place: | Nicomedia |
| Titles: | Martyr, Child Saint |
Vasilissa (300–309) 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 Anthimus. According to Russian Orthodox tradition, the torturers covered her whole body with wounds, but she remained faithful to Jesus Christ.
According to legend she was tortured with fire and wild beasts, yet remained unharmed. Her torturer, Alexander, seeing these wonders, repented and became a Christian. Vasilissa is said to have gone into a field, and fallen to her knees in prayer, thanking God for her endurance under torture, and she was killed while praying. She died in 309.