Siri

Siri is the main antaganist in the Rugrats and Wild Thornberries crossover called "Rugrats Go Wild". She first appears when Spike pees on her tail. They have a song battle (Since Eliza can talk to animals, we hear Spike speak for the first time, he is voiced by Bruce Willis) in which Spick wins. However, he slips out that the Rugrats kids are all alone in woods and Siri goes looking for them.

She appears again chasing them while they're going downhill in the baby carrige when a geyser goes off and washes her away.

http://www.youtube.com/watch?v=nMlQK5taX1Y&feature=related