St. Theodosius Nunatak (Bulgarian: нунатак Св. Теодосий, ‘Nunatak Sv. Teodosiy’ \'nu-na-tak sve-'ti te-o-'do-siy\) is the mostly ice-free ridge extending 1.9 km in northeast-southwest direction and 1 km wide, rising to 430 m[1] on the west side of Havre Mountains in northern Alexander Island, Antarctica. It surmounts Lennon Glacier to the north and Pipkov Glacier to the south-southeast.
The feature is named after the Bulgarian cleric and hermit St. Theodosius of Tarnovo (1300-1363), in connection with the settlement of Teodosievo in Northern Bulgaria.
St. Theodosius Nunatak is located at 69°13′13″S 72°04′36″W / 69.22028°S 72.07667°W, which is 3.13 km east-northeast of Buneva Point, 8.86 km south-southwest of Saint George Peak, 5.6 km west of Kutev Peak and 8.4 km northwest of Simon Peak. British mapping in 1991.