The 'bug' in your photos is a sowbug, also known as a woodlouse, pillbug, or roly-poly. They are not insects, but rather an isopod crustacean, more closely related to crayfish and shrimp. They live in forests, woods, meadows and gardens where they feed on all kinds of decaying plant matter. They require damp or moist conditions, and are most often active at night, hiding during the day under rocks, boards, leaf litter, etc. where there is moisture or high humidity. They are completely harmless to humans and don't normally harm garden plants. They do sometimes invade houses, although they don't normally live there and do no damage. Usually they are seeking moist conditions when it becomes too dry outdoors. They may also enter houses if their outside habitats are flooded from excess rain or snowmelt. They normally enter through cracks and crevices around basement windows, under doors, or from crawl spaces, and move to other areas along the outside of water pipes. This may be why you are seeing them in the bathroom, or because that is the most humid part of the home. These home invasions are usually temporary or seasonal, and these bugs just don't survive indoors because the conditions are too dry. However, if you are continually seeing these bugs inside your home, it may be an indication you have excess dampness, humidity, or other moisture/mold problems that are attracting them. To prevent them from entering, fix weather stripping under doors and around windows, caulk or seal openings around pipes and any other openings that might allow them access from the outside. I have included some links below to websites with more information about these bugs.

https://en.wikipedia.org/wiki/Woodlouse

http://www.ipm.iastate.edu/ipm/iiin/sowbus.html

http://extension.uidaho.edu/clearwater/files/2014/11/Homeowner-Guide-to-Pillbugs-and-Sowbugs.pdf