Darth Vader is a playable character in these games, but you unlock him through normal gameplay by completing specific levels or objectives.
Here's how you can unlock Darth Vader in Lego Star Wars: The Complete Saga:
* Episode IV: A New Hope - You can unlock Darth Vader by completing the level "The Death Star" on any difficulty.
* Episode V: The Empire Strikes Back - You can unlock him by completing the level "The Cloud City" on any difficulty.
You can also unlock Darth Vader by collecting enough Minikits (small, collectible items scattered throughout each level) or by achieving certain achievements within the game.
Remember, there are no cheat codes in Lego Star Wars to unlock characters. It's all about playing the game and enjoying the journey to unlocking your favorite characters.