Rat - The RuneScape Wiki

Rats are small animals which can be found in numerous locations, mostly in cities, sewers and dungeons. They are best found outside and on the ground floor[UK]1st floor[US] of Lumbridge Castle. Their tails are most commonly used for the completion of the Witch's Potion miniquest, and they are one of the weakest creatures in RuneScape. The only rats that drop bones are those in the Stronghold of Security. They are good for training on for new players as they have low life points and defence and respawn in only a few seconds, but they can be hard to click as they're small and move very fast.

Rat, RuneScape Wiki

Angry giant rat - The RuneScape Wiki

Rat - The RuneScape Wiki

You Doity Rat, RuneScape Wiki

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Hell-Rat - The RuneScape Wiki

Update:Scurrius, The Rat King - Mid-Level, PvM Boss - OSRS Wiki

Brine Rat Cavern - OSRS Wiki

Ratcatchers, RuneScape Wiki

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Rat's paper - The RuneScape Wiki