Order 65, the predecessor to Order 66, could have been used by the Jedi against Palpatine, but he protected himself from it. The reason Order 65 was not used against Palpatine was likely because the Jedi lacked confidence that the Senate would declare him unfit.
Order 65: In the event of either (i) a majority in the Senate declaring the Supreme Commander (Chancellor) to be unfit to issue orders, or (ii) the Security Council declaring him to be unfit to issue orders, and an authenticated order being received by the GAR, commanders shall be authorized to detain the Supreme ...
Order 99 was an order arranged by Jedi Master CaptainR1. It turned the storm troopers back to side of the new Republic. During the clone wars, clone commando "Roger" refused Order 66. He was very close to the Jedi he was fighting with.
The First Order is a fictional military movement and rump state in the Star Wars franchise, introduced in the 2015 film The Force Awakens. It is formed following the fall of the Galactic Empire after the events of Return of the Jedi (1983).
Order 69(AKA "clean up") was the idea to kill the entire clone army in one sitting, leaving the Jedi defenseless and exposed by the sudden departure. Palpatine knows the Jedi's weakness is empathy and most will try to help the clones and now it should be easy to either drive the Jedi into hiding or have them killed.
Star Wars Legends Introduced The Perfect Contingency Against Palpatine - Order 65. Order 65 was potentially the greatest threat to Palpatine's power, as it would authorize the GAR to detain the Supreme Chancellor (with lethal force if necessary).
All clones were given a behavioral modification biochip that could be activated by remote order via voice command; Supreme Chancellor Sheev Palpatine, for example, only needed to tell clones to execute Order 66, and the order was carried out.
Order 33: Kill half the Jedi. Order 34: Start planning for Death Star 3. Order 35: Keep those meddling kids away from Anakin. Order 36: Clean Palpatine's office.
Some clones resisted Palpatine's Order 66 in canon and Legends, helped the Jedi escape, and chose not to obey. Clones like Rex, Kix, Gregor, and ARC Troopers removed inhibitor chips and preserved their free will post-Order 66.
So, it's likely Yoda didn't want to interfere and alter the future, as he'd be at risk of preventing the Sith from being defeated many years later. While Yoda sensed that the Sith's plan involved the Clones, it was too late to prevent Order 66.
The Clone Wars Would Have Entered A New Phase If Order 66 Failed. Instead of fighting droids, the clone army would be repurposed to fight Jedi. On the bright side, this would mean the clones wouldn't be cast aside as they are after Revenge of the Sith.
As both a Sith and the ruler of the Empire, Palpatine took advantage of his clone resources by indoctrinating them with an order to kill Vader. Order 151 is also a credit to the incredible fighting prowess of Clone Troopers, even with their free will removed.
Some clones disobeyed the infamous order than decimated the Jedi order, and refused to execute it. SOME of these Clones include; Captain Rex: Captain Rex, as most know removed his chip that would later be the way that Palpatine would execute order 66.
Order 66, also known as Clone Protocol 66, was one of a series of contingency orders that the clone troopers of the Grand Army of the Republic were secretly trained to prepare for during their growth. The order branded the Jedi as traitors of the Republic and called for their immediate execution without question.
The Executive Order Codes for the Grand Army of the Republic, also known as the 150 general orders, were a set of directives memorized by every clone trooper of the Grand Army of the Galactic Republic.
The order was only documented being used once, in 18 BBY, where Obi-Wan Kenobi and Ferus Olin were attempting to escape Imperial patrols. This happened while Olin was in hiding on Bellassa in the city of Ussa. However, Kenobi believed that the clones would not honor their ultimatum and execute the prisoners anyways.
