Mark:  Peter's "son" (at least spiritually) - Synoptic Gospel

Written as early as 50, as late as 75 or 80 (multiple sources)

• 1st Gospel written and is the first real narrative of Jesus' life.
• Mark is telling the story with a focus on the death/resurrection - an must have believed this was the primary point of importance - they key to Jesus' identity as the Messiah.
• He, and the other authors, were crafting their message from the standpoint of being early theologians, rather than just "reporters", so their presentations are crafted to reinforce their message, not just record events.
• Mark writes in a way that enforces over and over that the disciples kept being unable to recognize what the "outcasts" of society saw - that he was more than just a miracle worker (something common in Jesus' times).  The disciples had trouble really "getting it" so to speak.
• Could have been written shortly after the war between Rome and Judea (post 70 AD)  that destroyed the temple (L. Michael White), which would explain the focus on extreme persecution.
  
• Jesus' ministry begins in Galilee and ends in Jerusalem according to Mark.
• Mark provides the basic plot (sets the stage) for Matthew and Luke, who were both familiar with Mark's gospel before telling their own stories (so these 3 are more similar, thus "synoptic").
• The Gospels are more about evangelism and "advertising" the good news rather than trying to be biographies.
• The gospels, Mark included, couldn't have veered too far from historical truth, as they were written for audiences who knew of Jesus already, so there was a significant level of accountability for accuracy, even though they weren't meant to be "history" books.

Luke: a physician - Synoptic Gospel

Written as early as 59, as late as 95 (multiple sources), with recent publications trending more towards the year 59 AD.

Luke interviewed eye-witnesses (was not an eye-witness himself), and collated his findings in the book of Luke.  He was Paul's coworker.  Luke also likely knew of and used the Gospel of Mark as a starting point.

"Luke is the evangelist and [most likely] the author of the gospel bearing his name and the Acts of the Apostles.  The materials found in Scripture referring to the life of Luke are scanty and seem to yield the following results: (1) Luke was of Gentile origin. This is inferred from the fact that he is not reckoned among those “who are from the circumcision” (Colossians 4:11; cf. v. 14). When and how he became a physician is not known. (2) He was not one of the “eyewitnesses and servants of the word” (Luke 1:2). (3) On the supposition of Luke’s being the author of the Acts we gather from those passages in which the first person we is employed that he joined Paul’s company at Troas and sailed with them to Macedonia (Acts 16:10-11). He accompanied Paul as far as Philippi (Acts 16:25-17:1) but did not share his persecution or leave the city, for here the third person theywe does not reappear until Paul comes to Philippi at the end of his third journey (Acts 20:6), from which it is inferred that Luke spent the intervening time—a period of seven or eight years—in the city or neighborhood; and as the we continues to the end of the book, that Luke remained with Paul during his journey to Jerusalem (Acts 20:6-21:18), was that apostle’s companion to Rome (Acts 27:1), sharing his shipwreck (Acts 28:2), and reaching the imperial city by way of Syracuse and Puteoli (Acts 28:12-16). According to the epistles he continued to be one of Paul’s “fellow workers” till the end of his first imprisonment (Philemon 24; Colossians 4:14). The last glimpse of the “beloved physician” discovers him to be faithful amid general defection (2 Timothy 4:11). Tradition since the time of Gregory of Nazianzus makes Luke a martyr, yet not unanimously, since accounts of a natural death slip in. Where he died remains a question; certainly not in Rome with Paul, for his writings are far later (Meyer, Com., on Luke, in introduction)."    www.bible.org

John: a fisherman

Written last of 4 Gospels, likely around or shortly after 95

• Written probably about 95, or a little later (per Dr. L. Michael White), but difficult to know exact date of the gospel's creation.
  
• John was an eyewitness, and one of the first disciples of Jesus.  (www.bible.org)
  
• John lived to be older than any of the other writers, and therefore was likely familiar with their accounts, which may have influenced what he chose to expand upon in his book. (www.bible.org)
  

"( “Jehovah is gracious”). The son of Zebedee, a fisherman on the Sea of Galilee, (Mark 1:19-20; Luke 5:10), and Salome (Matthew 27:56; cf. Mark 15:40). We have no information respecting the religious character or personal participation of Zebedee in the events of the gospel history, but John’s mother was one of the women who followed Jesus even to His crucifixion."     www.bible.org

"Internal evidence that the author is “the disciple whom Jesus loved,” who also leaned on His breast at supper (John 21:20, cf. 21:7), and that this is the apostle John, is supported by numerous lines of evidence. (1) He was a contemporary of the events described. The writer was known to the high priest and entered the high priest’s residence in company with Jesus (John 18:15). He alone narrates the fact that it was the high priest’s servant whose ear Peter cut off (John 18:10). He deals with questions about the period before the destruction of Jerusalem and not with controversies of the second century when Gnostic and Ebionite defections were active (cf. John 6:15; 11:47-50). Numerous other details point to the contemporary scene. (2) He was a Jew of Palestine. He shows acquaintance with Heb., as is shown by the book’s opening words (cf. Genesis 1:1). Three times he quotes from the Heb. (John 12:40; 13:18; 19:37). He knows intimately the Hebrew festivals, that of Passover (John 21:13, 23; 6:4; 13:1; 18:28), the Feast of Booths (John 7:2; Tabernacles, KJV), and the Feast of Dedication (John 10:22). Jewish customs and habits of thought are familiar to him, such as questions of purification (John 3:25; 11:55), marriage customs, especially the way of arranging waterpots (John 2:1-10); Jewish burial customs (John 11:38, 44; 19:31, 40). He shows firsthand knowledge of Palestine, that there is a descent from Cana to the Sea of Galilee (John 2:12) and that Jacob’s well is deep (John 4:11). He is familiar with such places as Ephraim (John 11:54), Aenon (John 3:23), Mt. Gerizim (John 4:20), Jerusalem and the Kidron (John 18:1), Bethesda and Siloam (John 5:2; 9:7), and Golgotha (John 19:17; etc.). (3) He was John, the beloved apostle. This is a general deduction sustained from the above facts. He indicates the hours of events recounted (John 1:39; 4:6, 52; 19:14). He reports quotations of Philip (John 6:7; 14:8), Thomas (John 11:16; 14:5), Judas (John 14:22), and Andrew (John 6:8-9). He leaned on Jesus’ breast at the Last Supper (John 13:23-25) and was numbered among the three, Peter, James, and John. Moreover, Peter is distinguished from the author by name, as in John 1:41-42; 13:6, 8, and James had suffered martyrdom long before the writing of the gospel (Acts 12:2). He characteristically introduces himself (John 13:23; 19:26; 20:2; 21:7, 20). These general facts make it difficult to escape the conclusion that John the apostle wrote the fourth gospel."    www.bible.org