The Book of Moroni
The sole original author of the book of Moroni was Moroni himself. Keep in mind that this is an unabridged record written by Moroni's own hand. These writings of Moroni serve almost as an appendix to the Book of Mormon containing some items of practical instruction, a sermon of his father Mormon, some epistles from his father, and his own final testimony and farewell.
Just for fun, let us summarize, the parts of the Book of Mormon that were not abridged by Mormon. They include: the first six books: 1 Nephi through Omni, the Words of Mormon (written by Mormon on the last page of the small plates of Nephi), the title page (written by Moroni on the final page of the plates of Mormon), chapters 6-9 of the book of Mormon (Chapters 1-5 were Mormon's abridgment of the longer record he had made of his own history and recorded onto the large plates of Nephi. Mormon later wrote chapters 6 and 7, and Moroni wrote chapters 8 and 9, directly onto the plates of Mormon), the book of Ether (written by Moroni), and the book of Moroni (see the supplemental article, Those Confusing Book of Mormon Plates).
Chapter Outline of Moroni
A brief outline of the book of Ether, worth committing to memory, is as follows:
Moroni 4-5 Sacramental Prayers
Moroni 7 Mormon's Teachings on Faith, Hope, and Charity
Moroni Chapter 1
1 Now I, Moroni, after having made an end of abridging the account of the people of Jared, I had supposed not to have written more, but I have not as yet perished; and I make not myself known to the Lamanites lest they should destroy me.
2 For behold, their wars are exceedingly fierce among themselves; and because of their hatred they put to death every Nephite that will not deny the Christ.
3 And I, Moroni, will not deny the Christ; wherefore, I wander whithersoever I can for the safety of mine own life.
4 Wherefore, I write a few more things, contrary to that which I had supposed; for I had supposed not to have written any more; but I write a few more things, that perhaps they may be of worth unto my brethren, the Lamanites, in some future day, according to the will of the Lord.
verse 4 It is interesting that Moroni had the impression that his writings will be of particular value to the latter-day descendants of the Lamanites. When he wrote the title page for the Book of Mormon onto the last page of the plates of Mormon, he named his "target audiences" for the book. Note the order in which he named them: "Wherefore, it is an abridgment of the record of the people of Nephi, and also of the Lamanites-Written to the Lamanites, who are a remnant of the house of Israel; and also to Jew and Gentile." Obviously his feelings for his own people were strong. It is also obvious that the Lord regards the purpose of the Book of Mormon to be, at least in part, a witness to the latter- day Lamanites: "And for this very purpose are these plates preserved, which contain these records-that the promises of the Lord might be fulfilled, which he made to his people; And that the Lamanites might come to the knowledge of their fathers, and that they might know the promises of the Lord, and that they may believe the gospel and rely upon the merits of Jesus Christ, and be glorified through faith in his name, and that through their repentance they might be saved" (D&C 3:19-20).