The cat was the first pet released in the realm of Runescape. It is currently is one of the older aspects of the game being introduced late 2003. On its release the pet was one of the most popular items with them being seen everywhere. Although the appearance of cats in everyday Runescape activities died down with the introduction of summoning in 2008.
A player can acquire a cat by completing Gertrude's Cat and training their kitten which will take a few hours. After turning the kitten into a cat the player has many options with it including dyeing it in the mini quest "Purple Cat", which can be completed after doing Swept Away, selling it in West Ardougne for 100 death runes (after completing Plague City), letting it become an overgrown cat or even turning it into a hellcat with Evil Dave's section of Recipe for Disaster.
The cat has many uses including catching rats and being the main part of several quests that result in the player being able to speak with the cat using a Catspeak amulet. The full list of cat Involved quests are below.
Do No Evil
Icthlarin's Little Helper
A Tale of Two Cats
Freeing Evil Dave (Sub Quest for Recipe For Disaster)