Architeuthis dux (4 - 10 m long)

http://www.futura-sciences.com/fr/news/t/zoologie/d/en-video-un-calmar-geant-filme-pour-la-premiere-fois_44017/

The largest living octopus is probably Enteroctopus dofleini, also known as the North Pacific giant octopus, reaching a length of over 6m and maximum recorded weight of 71 kg (156 lb). The largest living squid is probably the Colossal Squid, Mesonychoteuthis hamiltoni (http://en.wikipedia.org/wiki/File:Colossal_squid_caught_in_February_2007.jpg ), which replaced Architeuthis dux as the record holder in 2007, but it is a little harder to say for sure because they are only known from a couple of immature or incomplete specimens, which put the max size at about 12-14m (comparable to Architeuthis) and about 495kg. Based on these estimates, it is currently believed to be the largest living invertebrate. Someone has taken the time to compile a nice list of maximum sizes in a Wiki entry online here: http://en.wikipedia.org/wiki/Cephalopod_size

http://tolweb.org/Mesonychoteuthis_hamiltoni/19556