Saint Justus of Trieste is a Roman Catholic saint.
According to his passio, he was a citizen of Triest in Italy, known for his works and charities. When charges of being a Christian were brought against him by his fellow citizens, he was tried according to Roman law. Since he refused to sacrifice to the Roman gods, he was found guilty of sacrilegium and sentenced to death by drowning. According to a local tradition, he was thrown from a small boat into the Gulf of Triest, offshore the present promontorio of Sant'Andrea.
On the night of Justus' death the presbyter Sebastian was told in a dream that Justus' body had been washed ashore in spite of the weights meant to hold it down. Sebastian gathered his fellow believers and they went searching for the body, which they found on what is today Riva Grumula. Justus was then buried not far from the shore where he had been found. In late antique times the area near Piazza Hortis in Trieste was a cemeterial one and there is a good possibility that the former basilica of the Holy Martyrs at the corner of Via Ciamician and Via Duca d'Aosta was built on Justus' tomb.