The term 'Fierce One' can be represented by two crossword solutions: BEARCAT (7 letters) and TIGER (5 letters). A BEARCAT is a mammal native to Southeast Asia, also known as a binturong. It is related to the civet and has a bear-like appearance. The TIGER is a large cat native to much of Eurasia and parts of Africa. It is the largest of the four big cats and is an apex predator, meaning it is at the top of its food chain. Both the BEARCAT and the TIGER are fierce animals that are known for their strength and power.