Star Trek: Deep Space Nine1993

Odo:
How do you justify the deaths of so many people?

Female Shapeshifter:
The Solids have always been a threat to us. That's the only justification we need.

Odo:
But these Solids have never harmed you. They travel the galaxy in order to expand their knowledge, just as you once did.

Female Shapeshifter:
The Solids are nothing like us.

Odo:
No - I suppose they're not. And neither am I.