According to Luke 9:28-36, Elias (the New Testament spelling of Elijah) and Moses met with Jesus on the mount. We even know what they talked about: "And, behold, there talked with him two men, which were Moses and Elias: Who appeared in glory, and spake of his decease which he should accomplish at Jerusalem" (Luke 9:30-31). They spoke of the upcoming crucifixion ("decease") of Jesus Christ.
Let me mention one interesting thing about the meeting on the Mount of Transfiguration. Jesus went up and took three of His disciples: Peter, James, and John. That makes four people. Then, they were met by Elijah and Moses. That makes a total of six. Finally, the Father comes in a cloud and says, "This is my beloved Son: hear him" (Luke 9:35). That makes seven on the mount. Seven in the Bible is the number of perfection.