My original reply was going to be: "Hello, my name is Inigo Montoya. You killed my Father. Prepare to die." but that has already been posted. I thusly submit quotes of slightly lesser epicness.
"Freedom is the right of all sentient beings!" Originally attributed to the G1 Optimus Prime according to his profile card, first actual use in the Beast Wars episode 'Optimal Situation' episode one of season 3, finally featured in Transformers: Rise of the Fallen this past summer.
"Well that's just prime." - Optimus Primal, Beast Wars.
"Vae Victus!" - Kain, Blood Omen: The Legacy of Kain (Latin: Suffering/Woe to the conquered.) This series had SO MANY epic quotes it would be impossible to list them all, so I'll stick with the thing that was shouted about every twelve seconds if you were mobbed by enemies in the first game. I think that qualifies it as a catch phrase.
And for my submission as an epic quote, I submit a two-parter.
"The rodent's words, give off the stench of truth. Destiny has one great test in store for us all. Has mine already come, and have I failed it? A deed once done, cannot be undone, but perhaps it may yet be mitigated."
"Tell my tale to those who ask. Tell it truly, the evil deeds along with the good, and let me be judged accordingly. The rest, is silence."
Dinobot, Beast Wars, Code of Hero, season two, episode nine.