calibre - Ebook manager, viewer & converter
Tachiyomi - A free and open source manga reader for Android.
FBReader - FBReader is an e-book reader for various platforms. Features:
YACReader - Download YACReader for your platform. Windows, Linux, MacOSX. And enjoy you comic books cbr cbz with the best comic reader.
NeeView - Display two images simultaneously
IrfanView - IrfanView ... one of the most popular viewers worldwide.