Matthias Stom or Matthias Stomer (c. 1600 – after 1652) was a Dutch golden age painter considered one of the masters of Utrecht Caravaggism. Other variants of his name are Matthias Stohom or Stomma, Matheo Schem and Matteo Tomar. Stom spent most of his artistic life in Italy, and 200 of his works have been preserved.
It is conjectured that Stom was born at Amersfoort or in the Utrecht area, but many details of his life are vague. An early mention of Stom was around 1630, when he lived in the same location as Paulus Bor had lived a few years earlier. He was a pupil of Gerard van Honthorst in Rome after 1615.
He remained in Rome until 1632, after which he traveled to Naples, where he stayed until 1640. He then moved to Palermo, and delivered paintings for churches in Caccamo and Monreale. He sold three paintings to Antonio Ruffo, duke of Messina. It is speculated that he died in Sicily, or alternatively in Northern Italy, where in 1652 he painted an altar piece for the church in Chiuduno.
His son or grandson, Mattia (il giovane) Stomer (1649–1702), also was a painter.
Stom was influenced by the Baroque painter Caravaggio and his followers, utilizing their mastery of chiaroscuro. His work typically features religious scenes. He is appreciated for his psychology and noted for his "distinctive claylike treatment of flesh".