Dragonheart has something known as the Old Code. It was apparently the creed that King Arthur's knights lived by:
A Knight is sworn to Valor. His Heart knows only Virtue. His Blade Defends the Helpless. His Strength Upholds the Weak. His Word speaks only Truth. His Wrath Undoes the Wicked!
It also has an oath of service:
Call when you've need of me. Ask what you will of me. My sword — and my service — are yours.
In the novelization, the Code in full is revealed:
Inside the Table's circle, Under the Sacred Sword, A Knight must vow to follow The Code that is unending. Unending as the Table - A Ring by Honour bound.
A Knight is sworn to Valour. His Heart knows only Virtue. His Blade defends the Helpless. His Might upholds the Weak. His Word speaks only Truth. His Wrath undoes the Wicked.
The Right can never die If one man still recalls. The Words are not forgot If one voice speaks them clear. The Code forever shines If one heart holds it bright.
Pulp Fiction: "The path of the righteous man is beset on all sides by the iniquities of the selfish and the tyrannies of evil men..." However, Jules chose it just because it sounds cool, and he's still trying to figure out whether he's the man described in it.
This was cribbed from the Sonny Chiba classic "The Bodyguard," one of Tarantino's favorite grindhouse flicks.
"At other schools, they send young girls unprepared into a cold merciless world. But here at St. Trinian's, it is the merciless world which must be prepared."
Arguably, the school songs also qualify. The version from 1954:
Maidens of St Trinian's, gird your armour on. Grab the nearest weapon; never mind which one. The battle's to the strongest; might is always right. Trample on the weakest; glory in their plight.
St Trinian's! St Trinian's! Our battle cry. St Trinian's! St Trinian's! Will never die.
Stride towards your fortune boldly on your way, Never once forgetting there's one born every day. Let our motto be broadcast: "get your blow in first!" She who draws the sword last always comes off worst.
And the chorus and tag of the song from the 2007 film:
We are the best So screw the rest We do as we damn well please Until the end St. Trinian's Defenders of anarchy
Victorious Rebellious We do as we damn well please Until the end St. Trinian's Defenders of anarchy
The 13th Warrior (this is actually a prayer for the dead but they use it like this trope):
300 used the actual Spartan creed of: "Come home with this shield or upon it." Dead soldiers were carried home on their shields, and victorious ones would carry their shields back, but cowards who ran from battle would throw their heavy shields away.
"No retreat! No surrender!"
In his last film role in The Shootist John Wayne's character is a gunfighter with this creed:
"I won't be wronged, I won't be insulted and I won't be laid a hand on. I don't do these things to other people, and I require the same of them!"
In the crime thriller The Boondock Saints, the main characters would give a little prayer before executing a mafioso:
"And Shepherds we shall be For thee, my Lord, for thee. Power hath descended forth from Thy hand Our feet may swiftly carry out Thy command. So we shall flow a river forth to Thee And teeming with souls shall it ever be. In Nomine Patri, Et Fili, Et Spiritus Sancti."
"And when I raise my flashing sword And my hand takes hold in judgment, I will take vengeance upon mine enemies And I will repay those who hate me. O Lord, raise me to Thy right hand And count me among Thy saints."
"Whosoever sheds man's blood, by man shall his blood be shed. For in the image of God made he man." "Destroy that which is evil. So that which is good may flourish." "And I shall count thee among my favored sheep. And you shall have the protection of all the angels in heaven." "Never shall innocent blood be shed. Yet the blood of the wicked shall flow like a river. The three shall spread their blackened wings and be the vengeful striking hammer of God."
And in the sequel, two characters end a speech on manliness with this golden nugget of badassitude:
Rocco:Men do not cry. Men do not pout. Men check you on the fucking jaw, AND SAY...
Does the opening song from At World's End count? Probably not the first couple of lines, but...
The king and his men, stole the queen from her bed, And bound her in her bones. The seas be ours, and by the powers Where we will, we'll roam. Yo, ho, altogether, Hoist the colors high. Heave, ho, thieves and beggars, Never shall we die!
From Tall Tales: "Protect the land, defend the defenseless, and never spit in front of women or children." *spits*
From Men of Honor: "The Navy Diver is not a fighting man, he is a salvage expert. If it is lost underwater, he finds it. If it's sunk, he brings it up. If it's in the way, he moves it. If he's lucky, he will die young, 200 feet beneath the waves, for that is the closest he'll ever get to being a hero. Hell, I don't know why anybody'd want to be a Navy diver."
"I am the master of Liu Sang School of martial arts. Now, I make a sincere wish. Hope all the Gods and Evils listen to me. From now on, I will rule over the whole world of martial arts. And I will devote myself to my beloved country. Until our country conquer China. If anyone wants to stop me, I will terminate it with no mercy. I will keep my promise."
From Battle: Los Angeles, the 2/5 Marines quote a WWI captain. "Retreat? Hell!"
Johnny Blaze: [to Mephistopheles after he attempts to take the power of the Ghost Rider from him] No. I'm gonna own this curse... and I'm gonna use it against you. Whenever innocent blood is spilt, it'll be my father's blood... and you'll find me there. A spirit of vengeance... fighting fire with fire.
Godfrey of Ibelin: Be without fear in the face of your enemies. Be brave and upright that God may love thee. Speak the truth always, even if it leads to your death. Safeguard the helpless and do no wrong. That is your oath.