God Reveals His Name to Moses in the Old Testament:

Exodus 3:13-14 says: Then Moses said to God, "Behold, I am going to the sons of Israel, and I shall say to them, 'The God of your fathers has sent me to you.' Now they may say to me, 'What is His name?' What shall I say to them?" And God said to Moses, "I AM WHO I AM"; and He said, "Thus you shall say to the sons of Israel, 'I AM has sent me to you.'" (NAS)

Moses said to God, "Suppose I go to the Israelites and say to them, 'The God of your fathers has sent me to you,' and they ask me, 'What is his name?' Then what shall I tell them?" God said to Moses, "I AM WHO I AM. This is what you are to say to the Israelites: 'I AM has sent me to you.'" (NIV)

Then Moses said to God, "Indeed, when I come to the children of Israel and say to them, 'The God of your fathers has sent me to you,' and they say to me, 'What is His name?' what shall I say to them?" And God said to Moses, "I AM WHO I AM." And He said, "Thus you shall say to the children of Israel, 'I AM has sent me to you.'" (NKJ)

And Moses said unto God, Behold, when I come unto the children of Israel, and shall say unto them, The God of your fathers hath sent me unto you; and they shall say to me, What is his name? What shall I say unto them? And God said unto Moses, I AM THAT I AM: and he said, Thus shalt thou say unto the children of Israel, I AM hath sent me unto you. (ASV)

And Moses said unto God, Behold, when I come unto the children of Israel, and shall say unto them, The God of your fathers hath sent me unto you; and they shall say to me, What is his name? what shall I say unto them? And God said unto Moses, I AM THAT I AM: and he said, Thus shalt thou say unto the children of Israel, I AM hath sent me unto you. (KJV)