Iris from Gamera III: Revenge of Iris. My absolute favorite movie of all time.
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Irys from Gamera 3: Revenge/Awakening of Iris/Irys. Yes it is still my favorite movie.

Story:

Irys begins its life as a stone egg, sealed within a small underground
temple in Nara village and guarded over by a family line named Moribe.
Local legend said it was the resting place of a demon called
Ryu-Sei-Cho. A stone of unknown origin is said to keep the demon dormant
as long as it's not moved.


A young girl named Ayana Hirasaka, left an orphan by the 1995 Gamera and Gyaos battle
and blaming Gamera for her parent's deaths, entered the cave on a dare
and moved the stone. In the process she and the latest son of the Mirobe
line discover both the egg and an amulet, similar to the one that
linked Asagi to Gamera in the first film. The egg later hatched, produced a Baby Irys (ベビー·イリス^?, Bebī Irisu).



Ayana gains a link to the creature via the amulet and feels a
kinship with the creature, stating at one point "Gamera killed its
family too"; driven by total hatred for Gamera, she raises Irys, naming
it after her dead pet cat, in hopes that it will become strong enough to
kill him for her. It was shown to have an affectionate nature, but this
is shown alongside the sinister way it eats and, later in the film, the
woodland animals it leaves dead.



It is not long before Irys it attempts to merge with Ayana, and
her actions show she's willingly letting it do so, by sealing her in a
cocoon. Moribe discovers her and cuts her free. She is then taken to a
hospital. While Ayana is gone, Irys grows into a giant monster in the
woods as it devours several villagers, including Ayana's adoptive
parents and brother. Shortly, the monster grows into its adult form.



The J.S.D.F.
quickly deploys and surrounds Irys as it sleeps, attempting to take it
out with machine guns and bazookas. Some of the soldiers are killed
before Irys takes to the sky and heads for Kyoto, where Ayana had been
transferred earlier. The JSDF sends two F-15s in an attempt to shoot
Irys down, but it is able to evade them and almost kills them. The
fighter pilots are saved by the sudden arrival of Gamera, who engages
Irys in a mid-air battle. The JSDF ends the battle by shooting at
Gamera, which slows him down and allows Irys to continue on to Kyoto.



Soon, Irys lands in Kyoto and fights Gamera on land with Ayana
watching and commanding to kill it. Irys manages to knock Gamera down
for the count and then attempts again to merge with Ayana; when Moribe
intervenes, the creature swats him aside and sucks her into its body
against her will. While inside, Ayana realizes that she fueled Irys'
destruction with her emotions - it was her hatred that led to the death
of her adopted parents, and Super Gyaos instead of Gamera actually
killed her parents. All seems lost until Gamera suddenly punches through
Irys' armor and rips Ayana out.



Infuriated, Irys pins Gamera's hand to a wall with its spear hand
and begins to absorb Gamera's energy. Its tentacles begin to form
plasma balls, when Gamera quickly uses a plasma ball himself to sever his own hand.
Irys fires the absorbed plasma balls at Gamera who uses his stump to
turn the plasma into a plasma fist. Gamera then uses the fist to slice through Irys' chest, killing it.

Source:http://godzilla.wikia.com/wiki/Irys