XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
nomacs - nomacs is a free, open source image viewer, which supports mu
digiKam - Professional Photo Management with the Power of Open Source
ImageGlass - You can use Image to view your digital images and photos of many different formats.