Varanus marathonensis, the Samos dragon, is an extinct species of monitor lizard from the middle to late Miocene of Greece and Spain, known from several specimens.

[1] Comparisons with other species of monitor lizards put its size between 60 and 80 cm (2.0 and 2.6 ft) in length, excluding the tail.

The fossil was found in the Turolian-age Mytilini Formation on the island of Samos and is currently housed in the American Museum of Natural History.

Another specimen originally described as "V. amnhophilis" is known from several bone fragments, including the right side of the braincase, a right quadrate bone, part of the palate and skull roof, the right coronoid process and glenoid region of the lower jaw, a piece of the clavicle, and five vertebrae.

The species name amnhophilis means 'lover of lamb', from the Greek αμνόζ (amnhos, 'lamb') and φιλiζ (philis, 'a lover of'), as a reference to the diet of the largest living monitor lizards, which often includes sheep-sized (and larger) mammals.