Megalocephalus (meaning "big head") is an extinct genus of baphetid tetrapodomorph from the late Carboniferous (Westphalian A-C) of the British Isles and the United States (Ohio).

[2] Megalocephalus pachycephalus is one of the most common large tetrapodomorphs from the Carboniferous of Britain, and is known from several sites in England, Scotland, and Ireland.

Two well-preserved skulls and associated jaw bones were found in Newsham in 1870 and 1871, though these were also mistakenly referred to a pre-existing genus, Loxomma.

The modern combination Megalocephalus pachycephalus was popularized by Eileen H. Beamont's 1977 redescription of available "loxommatid" fossils.

This species is from the fossiliferous coal mine of Linton, Ohio, and was originally named as "Leptophractus" lineolatus by E.D.

Another skull described in 1957 demonstrated that "Leptophractus" lineolatus was a species of Megalocephalus, as it showed several diagnostic traits of the genus.

[5] A 2009 phylogenetic analysis suggests that Megalocephalus is paraphyletic relative to Kyrinion, with M. pachycephalus closer to K. martilli than to M. lineolatus.