A gallery of examples of Tentacle Extension.
Tyki Mikk (D.Gray-man), in his awakened state, can extend many tentacles.
Uroboros injection (Resident Evil)
William Birkin (Resident Evil)
The Thing (Movie The Thing)
Las Plagas (Resident Evil)
Solidus Snake's (Metal Gear Solid 2: Sons of Liberty) exoskeleton comes equipped with "Snake Arms" that can strangle opponents and fire missiles.
James Heller (Prototype 2) using his tendrils.
Ultimate Spider-Man (Spider-Man: Shattered Dimensions)
The Shadow Blot (Epic Mickey)
Dark Gaia (Sonic Unleashed)
Nemesis's (Resident Evil) tentacles are sharp enough to penetrate human flesh and bone.
Alexia Ashford (Resident Evil)
The Elder God (Legacy of Kain) is little more than an amorphous mass of tentacles and eyes, the former of which it uses offensively to great effect.
The Dahaka (Prince of Persia: Warrior Within)
Laughing Octopus (Metal Gear Solid 4: Guns of the Patriots)
Doctor Octopus 2099 (Spider-Man: Shattered Dimensions)
Omega Red uses his carbonadium tentacles to great effect.
The fake Groudon (Pokemon: Jirachi Wish Maker)