calibre - Ebook manager, viewer & converter
Icecream Ebook Reader - Ebook Reader by Icecream Apps allows to read ebooks in several formats (EPUB, MOBI, FB2 and others). Download EPUB Reader for Windows.
Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
Adobe Digital Editions - ebook reader software
FBReader - FBReader is an e-book reader for various platforms. Features:
OverDRIVE - Make workspaces and sites automatically from Google Drive