« A painting requires a little mystery, some vagueness, and some fantasy. » ~ Edgar Degas
… and some tentacles, of course!
This painting of a chained barbarian confronted by an octopus (here to collect his liver, no doubt?) is the work of Bob Juanillo, an artist of which little is known, other than that he was active in the late 60s and early 70s, contributed to a lot of comics fanzines, and died at 30 (source). At least we know it from 1974!
To follow, the original art for a variant cover for Red Sonja vs. Thulsa Doom no. 1 (February 2006). The painting is by Gabriele Dell’Otto, an Italian artist who has done work for Marvel and DC. Tentacles or enormous snake-tail, you be the judge. As for powerful necromancer (and shape-shifter) Thulsa Doom, he is the brain-child of American author Robert E. Howard.
This painting by John Totleben appeared (as far as I can tell) somewhere in Timeslip Special Vol 1 no. 1 (August 26th, 1998). « The isotope itself was eventually dumped, as garbage, into the oceans, where it began mutating the ocean life. One of the mutates was an octopus who, developing high intelligence, and through unknown means, donned a mechanical suit. The isotope itself eventually went on to mutate all life on the planet. » (source) I giggled at the idea of an octopus donning a mechanical suit ‘through unknown means’. These cephalopods get into everything!
Finally, voici an unfinished painting by Frank Frazetta, entitled Death Dealer VII (the first Death Dealer was painted in 1973). Health issues (blurry vision, and a series of strokes) prevented Frazetta from finishing it, though his preliminary sketch was published in Rough Work (Spectrum Fantastic Art, 2007).