Cthulhu Mythos scholar Robert M. Price claims the irregular sonnet "The Kraken", written in 1830 by Alfred Tennyson, was a major inspiration for Lovecraft's story, as both reference a huge aquatic creature sleeping for an eternity at the bottom of the ocean and destined to emerge from its slumber in an apocalyptic age.
S. T. Joshi and David E. Schultz cited other literary inspirations: Guy de Maupassant's "The Horla" (1887), which Lovecraft described in Supernatural Horror in Literature as concerning "an invisible being who...sways the minds of others, and seems to be the vanguard of a horde of extraterrestrial organisms arrived on earth to subjugate and overwhelm mankind"; and Arthur Machen's "The Novel of the Black Seal" (1895), which uses the same method of piecing together of disassociated knowledge (including a random newspaper clipping) to reveal the survival of a horrific ancient being.
It is also assumed he got inspiration from William Scott-Elliot's The Story of Atlantis (1896) and The Lost Lemuria (1904), which Lovecraft read in 1926 shortly before he started to work on the story.
Price also notes that Lovecraft admired the work of Lord Dunsany, who wrote The Gods of Pegana (1905), which depicts a god constantly lulled to sleep to avoid the consequences of its reawakening. Another Dunsany work cited by Price is A Shop in Go-by Street (1919), which stated "the heaven of the gods who sleep", and "unhappy are they that hear some old god speak while he sleeps being still deep in slumber".
The "slight earthquake" mentioned in the story is likely the 1925 Charlevoix–Kamouraska earthquake.
S.T. Joshi has also cited A. Merritt's novella The Moon Pool (1918) which Lovecraft 'frequently rhapsodied about'. Joshi says that, 'Merritt's mention of a "moon-door" that, when tilted, leads the characters into a lower region of wonder and horror seems similar to the huge door whose inadvertent opening by the sailors causes Cthulhu to emerge from R'lyeh'.