God the Father

This is who we usually mean when we say "God". His name is usually rendered "Yahweh", an attempts transliterated the Hebrew into English. Sometimes it's given as "Jehovah". Either way, it means, "I AM", a reference to God's eternal nature.

He is the head of the Trinity in some way we can't understand. The Son and Holy Spirit defer to him. It was his idea to create, and his idea to redeem his creation. He is the originator of everything.

There's a lot more that could be said, but I'll leave it at that.