Moose Versus Two Silverbacks

Now here we have some high quality carnage. A moose can weigh in at up to 1500 lbs, while silverbacks max out at about 450 lbs.  

Lion vs Tiger

It's an age old question but my research leads me to believe that a fully grown male Siberian tiger takes down a fully grown male African lion.

Let's settle this.

Venom

As James pointed out, there are a number of wild card species which at the very least merit a draw in almost any battle. Why? Venom.

Five most venomous species:

 

5. Stonefish

4. Blue-Ringed Octopus

3. Inland Taipan Snake

2. Brazilian Wandering Spider

1. Box Jellyfish

And while we're on the subject, the ten most venomous snakes:

10. Western Brown

9. Death Adder

8. Giant Black Tiger

7. Western Tiger 

6. Beaked Sea Snake

5. Riesvie Tiger

4. Eastern Tiger

3. Taipan

2. Common (Eastern) Brown

1. Inland Taipan (or Fierce Snake)

I still don't understand why the Inland Taipan is so underrepresented. One bite from contains enough venom to kill 50 adult humans (or one Marc Tohme). Now that's high quality carnage.  

Bear Wars

Kodiak v. Polar. 

Large Male Chimp Versus...

1) APBT

2) 2 Male Baboons  

3) Troy Palamalu and Brian Dawkins

Chimp shown above is female but gives you an idea of what's underneath all that hair...