“John the Apostle” From Concise Bible Dictionary:

Son of Zebedee, and brother of James. James and John were fishermen, but when the Lord called them, they forsook all and followed Him. The Lord surnamed them BOANERGES, “sons of thunder.”
John, Peter, and James were the three selected to be with the Lord on the mount of transfiguration, and in the garden of Gethsemane. In the Acts of the Apostles John was with Peter when the lame man was healed, and they were both cast into prison. They boldly declared that they could not but speak the things they had seen and heard. John was associated with Peter in visiting the Samaritans, who had received the word preached by Philip, and through the laying on of their hands the Holy Spirit was given (Acts 8).
John was one of the apostles at Jerusalem who, when Paul went there, gave to him and Barnabas the right hand of fellowship, that they should go to the heathen (Gal. 2:99And when James, Cephas, and John, who seemed to be pillars, perceived the grace that was given unto me, they gave to me and Barnabas the right hands of fellowship; that we should go unto the heathen, and they unto the circumcision. (Galatians 2:9)). He was afterward banished to the Isle of Patmos, probably under the emperor Nero or Domitian; it is not known with certainty which, nor at what date. There he had the visions recorded in the Revelation. He also wrote the Gospel and the three Epistles bearing his name, which are generally judged to have been written after the other Gospels and Epistles.
John in his gospel calls himself “the disciple whom Jesus loved”; at the last Passover he leaned upon the bosom of Jesus, and to his care did the Lord when on the cross commend His mother.

“John the Baptist” From Concise Bible Dictionary:

Son of Zacharias, priest of the order of Abia, or Abijah (1 Chron. 24:1010The seventh to Hakkoz, the eighth to Abijah, (1 Chronicles 24:10)), and of Elizabeth, a descendant of Aaron, born when they were both old. The conception was foretold by the angel Gabriel, who announced that John was to be a Nazarite, and should be filled with the Holy Spirit from his birth. His mission was also foretold: in the spirit and power of Elias he would be the forerunner of Christ, and would call the people to repentance, according to the prophecy in Isaiah 40:33The voice of him that crieth in the wilderness, Prepare ye the way of the Lord, make straight in the desert a highway for our God. (Isaiah 40:3). All that is recorded of his early life is “the child grew, and waxed strong in spirit, and was in the deserts till the day of his showing unto Israel” (Luke 1:8080And the child grew, and waxed strong in spirit, and was in the deserts till the day of his showing unto Israel. (Luke 1:80)).
To the Pharisees and the Sadducees he was especially severe, calling them a “generation of vipers” (Matt. 3:77But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come? (Matthew 3:7)), but in Luke the multitude are so designated, for all must flee from the wrath to come, and bring forth fruits meet for repentance. The ax was laid to the root of the tree. There was One coming with the winnowing fan, who would divide the wheat from the chaff.
When the religious authorities at Jerusalem sent to John to ask who he was, he declared that he was not the Christ, nor Elias, nor “that prophet” (Deut. 18:15,1815The 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; (Deuteronomy 18:15)
18I will raise them up a Prophet from among their brethren, like unto thee, and will put my words in his mouth; and he shall speak unto them all that I shall command him. (Deuteronomy 18:18)
). He was “the voice of one crying in the wilderness, Make straight the way of the Lord,” as Isaiah had prophesied (John 1:19-2319And this is the record of John, when the Jews sent priests and Levites from Jerusalem to ask him, Who art thou? 20And he confessed, and denied not; but confessed, I am not the Christ. 21And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No. 22Then said they unto him, Who art thou? that we may give an answer to them that sent us. What sayest thou of thyself? 23He said, I am the voice of one crying in the wilderness, Make straight the way of the Lord, as said the prophet Esaias. (John 1:19‑23)). The Lord, in speaking of John, said, “Elias is indeed come” (Mark 9:1313But I say unto you, That Elias is indeed come, and they have done unto him whatsoever they listed, as it is written of him. (Mark 9:13)), which seems to clash with John 1:2121And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No. (John 1:21); another passage however explains it: “If ye will receive it, this is Elias which was for to come” (Matt. 11:1414And if ye will receive it, this is Elias, which was for to come. (Matthew 11:14)). He had come in the spirit and power of Elias, as foretold by Gabriel; and he was Elias to those who received him and who afterward followed the Lord, as Andrew and another in John 1:4040One of the two which heard John speak, and followed him, was Andrew, Simon Peter's brother. (John 1:40).
So far we have considered John’s official place as the forerunner of Christ, but in John’s gospel the Baptist’s testimony is given to the Lamb of God. He also adds, “I knew him not,” but he had been told that He upon whom he saw the Holy Spirit descend and remain was the Baptizer with the Holy Spirit; and he adds, “I saw, and bare record that this is the Son of God.” He may have known Jesus in a natural way, but his knowing Him as Son of God was by a divinely-given testimony. John proclaimed Jesus as “the Lamb of God that taketh away the sin of the world”; and in the hearing of two of his own disciples he said, “Behold the Lamb of God.” Jesus was to be the object of their hearts, and they followed Him. Afterward, when John was told that Jesus was baptizing, and that all the people were going to Him, he gave a remarkable answer: “He that hath the bride is the bridegroom; but the friend of the bridegroom, which standeth and heareth him, rejoiceth greatly because of the bridegroom’s voice: this my joy therefore is fulfilled. He must increase, but I must decrease.” John was the friend of the bridegroom. The Lord said that among those born of women no one was greater than John; but the least in the kingdom of heaven was greater than he, because the latter was in a new dispensation, John being connected with the law and the prophets of the old dispensation (Matt. 11:11-1311Verily I say unto you, Among them that are born of women there hath not risen a greater than John the Baptist: notwithstanding he that is least in the kingdom of heaven is greater than he. 12And from the days of John the Baptist until now the kingdom of heaven suffereth violence, and the violent take it by force. 13For all the prophets and the law prophesied until John. (Matthew 11:11‑13)).
While in prison John’s faith or patience seems in measure to have failed him, and he sent two of his disciples to the Lord with the question, “Art thou He that should come, or do we look for another?” He evidently had not apprehended the humiliation and rejection of the Messiah, and expected to have been delivered from prison by the power which he knew had been exercised in grace by the Lord. The Lord wrought various miracles while John’s disciples were there, and bade them tell him what they had seen and heard, adding, “Blessed is he, whosoever shall not be offended in Me” (Luke 7:19-2319And John calling unto him two of his disciples sent them to Jesus, saying, Art thou he that should come? or look we for another? 20When the men were come unto him, they said, John Baptist hath sent us unto thee, saying, Art thou he that should come? or look we for another? 21And in that same hour he cured many of their infirmities and plagues, and of evil spirits; and unto many that were blind he gave sight. 22Then Jesus answering said unto them, Go your way, and tell John what things ye have seen and heard; how that the blind see, the lame walk, the lepers are cleansed, the deaf hear, the dead are raised, to the poor the gospel is preached. 23And blessed is he, whosoever shall not be offended in me. (Luke 7:19‑23)).
It was because of John’s faithfulness in reproving the sins of Herod Antipas that he had been by him cast into prison. This led to his death through Salome and her guilty mother. John’s work was done; he was faithful unto death (Mark 6:14-2914And king Herod heard of him; (for his name was spread abroad:) and he said, That John the Baptist was risen from the dead, and therefore mighty works do show forth themselves in him. 15Others said, That it is Elias. And others said, That it is a prophet, or as one of the prophets. 16But when Herod heard thereof, he said, It is John, whom I beheaded: he is risen from the dead. 17For Herod himself had sent forth and laid hold upon John, and bound him in prison for Herodias' sake, his brother Philip's wife: for he had married her. 18For John had said unto Herod, It is not lawful for thee to have thy brother's wife. 19Therefore Herodias had a quarrel against him, and would have killed him; but she could not: 20For Herod feared John, knowing that he was a just man and an holy, and observed him; and when he heard him, he did many things, and heard him gladly. 21And when a convenient day was come, that Herod on his birthday made a supper to his lords, high captains, and chief estates of Galilee; 22And when the daughter of the said Herodias came in, and danced, and pleased Herod and them that sat with him, the king said unto the damsel, Ask of me whatsoever thou wilt, and I will give it thee. 23And he sware unto her, Whatsoever thou shalt ask of me, I will give it thee, unto the half of my kingdom. 24And she went forth, and said unto her mother, What shall I ask? And she said, The head of John the Baptist. 25And she came in straightway with haste unto the king, and asked, saying, I will that thou give me by and by in a charger the head of John the Baptist. 26And the king was exceeding sorry; yet for his oath's sake, and for their sakes which sat with him, he would not reject her. 27And immediately the king sent an executioner, and commanded his head to be brought: and he went and beheaded him in the prison, 28And brought his head in a charger, and gave it to the damsel: and the damsel gave it to her mother. 29And when his disciples heard of it, they came and took up his corpse, and laid it in a tomb. (Mark 6:14‑29)).

Strong’s Dictionary of Greek Words:

from 907; a baptizer, as an epithet of Christ's forerunner
KJV Usage: