God the Son

Heb 3:1 Wherefore, holy brethren, partakers of the heavenly calling, consider the Apostle and High Priest of our profession, Christ Jesus;
Heb 3:2 Who was faithful to him that appointed him, as also Moses was faithful in all his house.
Heb 3:3 For this man was counted worthy of more glory than Moses, inasmuch as he who hath builded the house hath more honour than the house.
Heb 3:4 For every house is builded by some man; but he that built all things is God.

Consider the description of Jesus given in these verses to the holy brethren, those who are called in Christ Jesus.

He was faithful to his calling as was Moses to those he was called to serve.

He was greater than Moses because Moses was a good steward over Israel, but Jesus created Israel. God chose a people beginning with Abraham, Jesus was with God and was God the Son.

Joh 8:58 Jesus said unto them, Verily, verily, I say unto you, Before Abraham was, I am.

Jesus was an apostle of God, sent on a mission as was Moses, by God the Father. Moses prophesied of one coming like him who would be greater than him.

Deu 18:15 The LORD thy God will raise up unto thee a Prophet from the midst of thee, of thy brethren, like unto me; unto him ye shall hearken;

Jesus is also our Great High Priest after the order of Melchisedec, who had no known beginning or end and he was greater than Abraham because Abraham gave tithes to him.

Jesus is God who created the worlds (John 1:1, Genesis 1:1,)

Heb 1:1 God, who at sundry times and in divers manners spake in time past unto the fathers by the prophets,
Heb 1:2 Hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds;
Heb 1:3 Who being the brightness of his glory, and the express image of his person, and upholding all things by the word of his power, when he had by himself purged our sins, sat down on the right hand of the Majesty on high;