One thing I learned from my father is to never give up, even when the odds are stacked against you.
[to himself, after Trunks is fatally wounded by Cell's blast] How could I let this happen to my son? He has sacrificed everything for me! And I have done nothing but ignore him! No! I won't give up on him! There is still time to change things! Cell has crossed me for the last time! He has tricked me in battle, mocked my Saiyan ancestry, but this...this time he's gone too far...he will pay the ultimate price...for what he has done to my son!
At last...it's over.
Wrong. It's over when I say it's over! [Cell smacks Vegeta away with one jab]
[after injuring Vegeta and Gohan] Why would Gohan sacrifice himself to save Vegeta? Hm...I will never understand the ways of these Saiyans. [Gohan and Vegeta are lying next to each other, badly bruised] Look at them. They belong together. They are both so...weak!
First I'll destroy you, then your friends, and then this worthless planet! But before I do, I want you to remember something! I will live forever!
These quotes come from Wikiquote's Dragon Ball Z pages and are available under the Creative Commons Attribution-ShareAlike License.