Who compiled the books in the bible into one single book?

The process of the canonization of the Old and New Testaments was complex and lengthy and was developed over many centuries.

The Old Testament (also known as Hebrew Bible) as a whole was canonized circa 100 CE while the Torah (first 5 books of OT) was canonized circa 400 BCE.

In the early centuries of the Christian church, there was no single New Testament canon that was universally recognized.

By the 4th and 5th centuries the existing 27-book canon of the New Testament was widely accepted with a few exceptions. Over time this was accepted by the Christian churches.