Clint Eastwood is the master of the memorable line, but I'll leave those to others. Here are some lines from other actors that stood out for me and in some cases a lot of other people too. I assume most of you will know the movies that go with the lines.
We're going to need a bigger boat"
"I'm your Huckleberry"
“No ******* ever won a war by dying for his country. He won it by making the other poor dumb ******* die for his country.”
"You *** up! You trusted us!"
Fat, drunk and stupid is no way to go through life son".
"I love the smell of napalm in the morning"
"I made him an offer he couldn't refuse"
"I am serious. And don't call me Shirley".
"When it comes down to making out, whenever possible, put on side one of Led Zeppelin IV"