This is Kali. She's the meanest of my three kitties by a mile, and she's only 4 months old! Her poor mum and sister need to sleep with one eye open, because if they so much as twitch, Kali will pounce claws first. It's not only her immediate family who suffer from her rage. I've lost count of the number of times she's woken me up in the morning by sinking her claws as far as she can into some sensitive part of my body (usually the soles of my feet). She also likes playing football with spiders and woodlice, and my gerbil and fish live in constant fear of their lives. 

But her meanest trait by far is her refusal to be litter trained. She lulls me into a false sense of security by making a big show of how she uses her litter box for a week or so, then I'll go out for an hour and come home to find stinky little presents all over the house and Kali laughing maniacally from her perch on top of the gerbil cage!