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.

A Border Collie competes in the Flyball during The World Dog Games at Acer Arena on October 31, 2009 in Sydney, Australia. (Photo by Brendon Thorne/Getty Images)

A mahout bathes his elephant in the river Sabarmati on a hot summer day in Ahmedabad, India May 21, 2017. (Photo by Amit Dave/Reuters)

Mourning woman. (Photo by Rich Legg/Getty Images/iStockphoto)

Russian policewomen dressed in Soviet Army styled uniforms take part in the Victory Day parade in Volgograd on May 9, 2018. Russia marks the 73 rd anniversary of the Soviet Union' s victory over Nazi Germany in World War Two. (Photo by Mladen Antonov/AFP Photo)

In this image released on November 22, English singer and songwriter Dua Lipa poses for the 2020 American Music Awards, broadcast on November 22, 2020 in London, England. (Photo by Gareth Cattermole/Getty Images for dcp)

Partners Juliet Hockaday (22) and Sarah Poole (22) pose for a portrait at All Things Go on the first day of the music festival, on September 28, 2024 in Columbia, MD. (Photo by Maansi Srivastava for the Washington Post)

A stuntman performs while riding a car inside the “Wall of Death” attraction during a fair in Bhaktapur April 20, 2015. (Photo by Navesh Chitrakar/Reuters)