The concept of fusing the God Cards together is a popular fan theory, but it's not a recognized card in the official game.
However, there are some interesting cards that involve the God Cards:
* "The Winged Dragon of Ra - Sphere Mode": A powerful version of Ra with a different summoning condition and effect.
* "The Triune God": A powerful monster that can be summoned using the three God Cards. However, it's not a fusion monster, and it doesn't combine the three into a single being.
* "The Three God Cards": A spell card that lets you summon one of the God Cards from your hand, but it doesn't involve fusing them together.
So, while you won't find an official fusion monster created by combining the three God Cards, the idea is certainly a popular one among Yu-Gi-Oh! fans!