In scholarly circles, Mark 16:9-20 is known as the "Marcan Appendix," because there are sound reasons for believing that the author of Mark did not write this passage. Textual evidence indicates that as far as original materials are concerned Mark should end at verse 8 with the statement about the women being too afraid to tell others what they had seen. Verses 9-20 were redacted by a later scribe.
 

My own edition of the American Standard Version affixed this footnote at the beginning of verse 9: "The two oldest Greek manuscripts, and some other authorities, omit from ver. 9 to the end. Some other authorities have a different ending to the Gospel." My NIV edition has a bracketed statement between verses 8 and 9: "The most reliable early manuscripts and other ancient witnesses do not have Mark 16: 9-20." Of the 17 versions of the New Testament in my personal library, 15 of them have reference notes to tell readers that this ending to Mark was not in the oldest and most reliable manuscripts.
 

One of the early manuscripts that did not include the Marcan Appendix was Codex Sinaiticus (4th-century A.D.), which ended Mark's gospel at 16:8. In Secrets of Mt. Sinai, James Bentley made this observation about the omission of the Marcan Appendix in Codex Sinaiticus:
 

The scribe who brought Mark's Gospel to an end in Codex Sinaiticus had no doubt that it finished at chapter 16, verse 8. He underlined the text with a fine artistic squiggle, and wrote, "The Gospel according to Mark." Immediately following begins the Gospel of Luke (p. 139).
 

Codex Sinaiticus is the only ancient Greek manuscript that contains the entire New Testament. The fact that it did not include the Marcan Appendix clearly suggests that the 4th-century scribes who copied it had before them a version of Mark that ended with 16:8. In the foreword to Bentley's book (p. 6), the renown pseudepigraphic scholar James H. Charlesworth pointed out that Codex Syriacus (a 5th-century translation), Codex Vaticanus (mid-4th century), and Codex Bobiensis (4th- or 5th-century Latin) are all early manuscripts that exclude the Marcan Appendix. In addition to these, approximately 100 early Armenian translations, as well as the two oldest Georgian translations, also omitted the appendix (Bentley, p. 179). Manuscripts written after Sinaiticus and Vaticanus have been found that contained the Marcan Appendix but with scribal notes in the margins that said the verses were not in older copies; others have been found that had dots or asterisks by the verses in the Marcan Appendix as if to signal that they were in some way different from the rest of the text (Bentley, p. 179). These facts give us compelling reasons for suspecting that the Marcan Appendix was indeed the redaction of a scribe who considered Mark's omission of postresurrection appearances to be an inadequate way to end the gospel.
 

In addition to the Marcan Appendix, some manuscripts ended Mark's gospel with other variations. Codex Washingtonensis (late 4th or early 5th century A.D.), for example, included the addition to 16:14 that is known as the Freer Logion. It is the underlined statement added to the following quotation of verse 14:
 

Later he appeared to the eleven themselves as they were sit- ting at the table; and he upbraided them for their lack of faith and stubbornness, because they had not believed those who saw him after he had risen. And they excused themselves, saying, "This age of lawlessness and unbelief is under Satan, who does not allow the truth and power of God to prevail over the unclean things of the spirits. Therefore reveal your righteousness now"--thus they spoke to Christ. And Christ replied to them, "The term of years of Satan's power has been fulfilled, but other terrible things draw near. And for those who have sinned I was handed over to death, that they may return to the truth and sin no more, that they may inherit the spiritual and imperishable glory of righteousness that is in heaven" (NRSV).
 

Other manuscripts added to verse 8 still another but much shorter ending than the Marcan Appendix: "And all that had been commanded them they (the women who had gone to the tomb--FT) told briefly to those around Peter. And afterward Jesus himself sent out through them, from east to west, the sacred and imperishable proclamation of eternal salvation" (NRSV), to which even other manuscripts added Amen.
 

If anything is clear from all this it should be that the ending to Mark's gospel has undergone considerable editing. What the original ending actually was may now be permanently lost in the wake of all this scribal tampering, but the scholastic consensus is that none of the variant endings-- the Marcan Appendix, the Freer Logion, and the "short ending"--were the work of the original writer. The reasons for that consensus are summarized in the following quotation from The New Jerome Biblical Commentary:
 

The longer ending, traditionally designated Mark 16:9-20, differs in vocabulary and style from the rest of the Gospel, is absent from the best and earliest mss. now available, and was absent from mss. in patristic times. It is most likely a 2nd-cent. compendium of appearance stories based primarily on Luke 24, with some influence from John 20.... The so-called shorter ending consists of the women's reports to Peter and Jesus' commis- sioning of the disciples to preach the gospel. Here too the non- Marcan language and the weak ms. evidence indicate that this passage did not close the Gospel.
 

The so-called Freer Logion in Codex W at 16:14 of the longer ending is a late gloss aimed at softening the condemnation of the disciples in 16:14. All the endings attached to Mark in the ms. tradition were added because scribes considered 16:1-8 inadequate as an ending (p. 629, emphasis added).
 

The stylistic and vocabulary differences referred to in this quotation are apparent even in English translations of the variant endings, but even without this consideration, suspicion is cast onto their authenticity by (1) the obvious attempt to reconcile Mark's ending with Luke's and John's accounts of postresurrection appearances and (2) the inconsistencies between the appendix and what Mark had said earlier in the chapter
 

What we have in the Marcan Appendix is an obviously bungled attempt to harmonize the ending of Mark's gospel with other accounts of postresurrection appearances.
 

To see a complete detailed list of Additions within the Bible

NT additions:

+GMk=Additions to Gospel of Mark, Mk16:9-20, c450ce

+GLk=Additions to Gospel of Luke, Lk22:19b-20,43-44, c150ce

+GJn=Additions to Gospel of John, Jn7:53-8:11, c400ce

ActW="Western" version of Luke's Acts of the Apostles, c.10% larger, c150ce

"Western Reviser" adds/subtracts from original Acts to produce "Western"

version which is 10% larger and found in Papyrus P29,38,48 & Codex Bezae (D)

{Who it was that was responsible for the additional information concerning

the apostolic age or where it came from is entirely unknown. According to F.

G. Kenyon, "What one would like to suppose (but for which there is no exter-

nal evidence), is that one of St. Paul's companions transcribed Luke's book

[Acts] (perhaps after the author's death), and inserted details of which he

had personal knowledge, & made other alterations in accordance with his own

taste in a matter on which he was entitled to regard himself as having auth-

ority equal to that of Luke."} [Textual Comm., Metzger, 3-438-06010-8, p272]

3Cor=3rd Corinthians, by Paul of Tarsus?, c58-170ce [Armenian Bible]

+1Jn=Additions to 1st Letter of John, Comma Johanneum: "in heaven, the Father,

the Word, and the Holy Ghost: and these three are one. And there are three

that bear witness in earth," [1Jn5:7b-8a(KJV)]; 1st found in the Latin book

"Liber Apologeticus" by the Gnostic Priscillian [p781,n21] c350ce, found in

only 4 Greek manuscripts!, all after 11th century! [Epis.John,Brown,p775-87]

Laod=Epistle to the Laodiceans (cf.Col4:16), c100-350ce [Vulgate Fuldensis]

OT additions:

+Est=Additions to Greek Esther of Septuagint (=LXX), c50bce

+Dan=Additions to Greek Daniel: Prayer of Azariah, Bel, Susanna, c100bce

Bar=Baruch (1 Baruch), written in Greek, c100bce

EpJr=Epistle of Jeremiah, Greek fragments found at Qumran Cave 7, c250bce

Baruch and Epistle of Jeremiah are additions to Greek Jeremiah of Septuagint

+Ps1=Additional Psalm 151, Qumran 11QPs(a)151, c150bce [Septuagint,Peshitta]

+Ps2=Additional Psalms 152-155, Qumran 11QPs(a)154,155; c150bce [Peshitta]

1Esd=1 Esdras, written in Greek, c100bce [LXX=Esdras A, Vulgate=Esdrae III]

2Esd=2 Esdras, c100ce [Vulgate=Esdrae IV] [Vulgate,Peshitta]

Tob=Tobit, 1 Hebrew and 3 Aramaic manuscripts found at Qumran Cave 4, c200bce

Jdt=Judith, written in Hebrew, c150bce

Wis=Wisdom (of Solomon), written in Greek, c100bce

Sir=Wisdom of Jesus ben Sirach (Ecclesiasticus), Qumran C. 2, Masada, c180bce

PrMn=Prayer of Manasseh (cf. 2Chr33:1-19), written in Jerusalem, c100bce

1Mac=1 Maccabees, Greek translation of lost Hebrew, c130bce [Septuagint]

2Mac=2 Maccabees, written in Greek, c120bce [Septuagint]

3Mac=3 Maccabees (Ptolemaica), written in Greek c25bce [Septuagint]

4Mac=4 Maccabees, written in Greek in Alexandria, c40ce [Septuagint]

PsSo=Psalms of Solomon, written in Hebrew in Jerusalem, c50bce [Septuagint]

ApBr=Apocalypse of Baruch (2Baruch=Syriac, 3Baruch=Greek), c100ce [Peshitta]

Enoc=Enoch, 8 Aramaic manuscripts found at Qumran Cave 4, c100bce [Ethiopian]

Jub=Jubilees, 10 Hebrew manuscripts found at Qumran 1,2,4, c100bce [Ethiopian]

Barn=Epistle of Barnabas, c100ce [Apostolic Fathers]

Herm=Shepherd of Hermas, written in Rome, c125ce [Apostolic Fathers]

Clem=1,2 Clement: 1=Pope to Corinth 95ce, 2=sermon c100ce [Apostolic Fathers]

T12P=Testaments of the 12 Patriarchs, Hebrew and Aramaic fragments found at

Qumran Caves 1 and 4, c100ce [Armenian Bible]