The Kraken ... for real

 An artist's reconstruction of a finned octopus of the species Nanaimoteuthis haggarti

that reached a length estimated at up to 18.6 meters (61.02 feet) and lived about 86 to 72 million years ago during the Cretaceous Period, released on April 23, 2026. 

Yohei Utsuki/Hokkaido University/Handout via REUTERS

The Kraken lived. Think about the smarts of this monster! The question to ask is, why is ocean life so small today. Boffins think it's the temperature along with the introduction of man and his baggage
as root causes of this happenstance.

Works for me.

The Kraken, the giant cephalopod of legend, was feared by sailors for centuries. Later interpretations suggested that it may have been based on sightings of the giant squid, which can be 10 meters long. Although they lived far too early to have been the source of the legend, Ikegami et al. describe fossil octopods from the late Cretaceous that truly would have fit the description of the monster, reaching up to 19 meters in length. Wear patterns on their jaws suggest that these octopods preyed upon the large reptiles present at the time, including plesiosaurs and mosasaurs. The authors interpret asymmetry in these wear patterns as an indication of corresponding asymmetry in behavior, suggesting complex brain development and, potentially, high intelligence. —Sacha Vignieri

Fig. 4. Body size estimation of Late Cretaceous octopuses.

The graph shows an allometric relationship between the length of the jaw and mantle in long-bodied species of extant finned octopus (tables S3 and S4) (31). The name of the corresponding species is shown along each growth curve. The sizes of N. jeletzkyi and N. haggarti based on their largest specimen are indicated by black vertical lines. Reconstruction of these two species, the extant giant squid (36), and gigantic vertebrate predators (37–40) in the Late Cretaceous are shown with their maximum total length.

A true apex without question.

A "colossal octopus" attacking ship, pen and wash[1] by Pierre Denys-Montfort,
engraved by Étienne Claude Voysard, 1801[2]

If the monster was alive today, this engraving would be for real. :)