20. Anakin killing the Tusken Raiders (Star Wars: Attack of the Clones)
Anakin suffers plenty throughout his lifetime, but the moment he finds that his mother has been tortured and she then dies in his arms is a crushing moment. It’s hard to blame him for reacting to his mother’s death by wanting to kill those responsible for it. Anakin takes it so much further than that, though.
Anakin completely slaughters the Tusken Raiders and we don’t even need to see the whole thing play out to know how bad it is. There’s no doubt in my mind that Anakin always had moments where he’d lean towards the dark side more than some of the other Jedi we see him interacting with over the years. It really feels like that starts with this moment.
While we don’t see the full thing play out, we do see Yoda’s reaction to it. Mace Windu comes in and asks him about it. He’s obviously concerned about Anakin and with good reason. That kind of anger is understandable, but it isn’t the Jedi way. It’s brought up time and time again how the Jedi aren’t ones to outright kill someone. At times, it can be to their detriment, but here it was out of pure anger. That was what was concerning to Yoda.