Full-time feline photographer Andrew Marttila from Washington, D.C., captured blissful expressions of various cats on catnip, which he used to compile a book, “Cats on Catnip”. The photographer dedicated his time to capturing the euphoric expressions of kitties high on catnip – and the results are absolutely hilarious. (Photo by Andrew Marttila/Caters News Agency)

Khan, a five-year-old male White Bengal tiger, looks on inside an open-air cage at the Royev Ruchey zoo in Krasnoyarsk, Russia, October 21, 2016. (Photo by Ilya Naymushin/Reuters)

Most pet cats will become timid or defensive when outdoors, but not Millie – after being adopted by her mountain-climbing owner Craig Armstrong, Millie has become a feline hiking and mountain-climbing legend.

Shironeko, also known as “Basket Cat”, is a Turkish van cat called “Shiro”, which is best known for his extremely relaxed demeanor and ability to balance things on his head, similar to Oolong the Pancake Bunny. The cat has been given several nicknames by its fans, most notably “Basket Cat” and “Zen Cat.”

Cat-Friend vs Dog-Friend, Two Humans Acting Like House Pets

A cat yawns at Nekorobi cat cafe on January 20, 2009 in Tokyo, Japan. Cat cafes, where people can spend time with their favorite cat for about 10 US dollars an hour, are now getting more popular with people living in urban areas. The regular customers are mainly in their 20's to 30's and seaking healing by cats, or people who cannot afford to have pets full time. Some visiters come to the cat cafe three times a week. (Photo by Junko Kimura/Getty Images)

Japanese embroidery artist Hiroko Kubota was in the process of making custom sized clothes for her smaller-framed son when he made a small request: could some of the shirts have cats on them? Kubota explains her son was somewhat obsessed with cats and had collected a small library of adorable images found around the web.