Cave of Wonders Guardian

The Cave of Wonders Guardian appears in Kingdom Hearts and Kingdom Hearts coded as the living entrance to the Cave of Wonders.

Kingdom Hearts
In Kingdom Hearts, Sora, Aladdin, Donald, and Goofy fight it after it was taken over by the Heartless and tried to destroy them. Once they destroy the dark power's source, which is located in his eyes (reached by climbing up its neck or by leaping onto it's face when it's buried in the dirt), the guardian returns to being an entrance to the Cave of Wonders, and continues to be so throughout the series.

Kingdom Hearts coded
In Kingdom Hearts coded, Jafar places a spell on the guardian and Sora must fight it to enter the Cave of Wonders.

Kingdom Hearts
First, the Cave of Wonders will emit lasers from its eyes, just like the Stealth Sneak did. It can either be reflected (particularly using Guard), or simply avoided. To attack the Cave of Wonders, you need to climb up its side, and then strike it. You do not want to be down where Donald and Goofy are, as the Cave of Wonders will be shooting lasers, exhaling fire and summoning Heartless in the process. If you do not find it easy to climb up the side of the Cave of Wonders, then wait until it dives its head down into the ground. Once this happens, climb up the back of its head. Should you run low on health, you can kill some of the nearby Heartless for some HP Balls. Or, you can go around to the back of the head and try and jump on its back, then run up to the head and attack (this could take some time). Alternatively, if you are good with magic, stand back and lock onto the eyes, using the Fire spell from a distance.

Trivia

 * Cave of Wonders Guardian is one of only eight enemies who do not have entries in Jiminy's Journal. The others are AntiSora, Bit Sniper, Chernabog, the Crank Tower, Glut, Shadow Sora, and World of Chaos.