Cranfillia fullagari, synonym Blechnum fullagarii,[2] is a fern in the family Blechnaceae.

The specific epithet honours James Fullagar, who collected plants on Lord Howe Island for the Royal Botanic Gardens, Melbourne.

[4] Although Mueller spelt the name Lomaria fullageri, using an e in the epithet, he referred to the surname "Fullagar".

[6][7] The spelling fullagarii is found in some sources;[3] Article 60.8 of the International Code of Nomenclature for algae, fungi, and plants only allows the use of a single "i" with names ending in "er" not "ar".

[9] The fern is endemic to Australia's subtropical Lord Howe Island in the Tasman Sea.