The Fellowship of the Ring is written by J.R.R. Tolkien. J.R.R. Tolkien wrote The Two Towers
[Human]: Do you know if Fellowship of the Ring is part of a series? [Assistant]: Yes, it is a serialized work written by JRR Tolkien [Human]: Is Lord of the Rings before or after?  Do you know? [Assistant]: The Fellowship of the Ring is part of the Lord of Rings series.  The Fellowship of the Ring is the first book. [Human]: Great.  What other Tolkein book could you recommend? 
Sure. He also wrote The Hobbit series of books, The Silmarillon and The Three Towers.