If it wasn't confirmed after five seasons of Breaking Bad, his brief cameo in El Camino definitely seals the deal - Walter White is evil. While the worst things Walter White does in pursuit of money and power are pretty obvious to anyone watching the show, there are also several more subtle examples of his maliciousness strewn throughout the series - evidence that the man they call Heisenberg was always the bad guy of the story.
It shouldn't take much to convince even the most dedicated Walt stans that cooking blue, taking lives, and infecting children are all evil deeds - but the misdeeds of Breaking Bad's protagonist go much deeper than that, and permeate the core of his being. A re-watch of the series with an eye for Walt White's immorality reveals a character who will do just about anything as long as it benefits him - and perhaps a man who broke bad long before he started manufacturing the purest substance on the underground market.
Walter White's actions toward Jesse Pinkman in "Ozymandias," episode 14 of the series' fifth season, are undeniably evil. He rats out Pinkman's hiding spot and hands him over to Jack Welker and his crew of white supremacists, assuming they will end his partner. Unfortunately, Jesse ends up in a much worse position as their servant.
Just before he and Jesse part ways, Walt informs his former partner that he was there when Jane Margolis passed:
I watched Jane [perish]. I was there. And I watched her [go]. I watched her OD and choke... I could have saved her. But I didn't.
Not only does Walter reveal this horrific truth in an attempt to further damage Jesse, but he also appears to take some degree of pleasure in delivering the emotional suckerpunch - a truly unforgivable act.
Walter White's nonlethal intoxication of young Brock Cantillo is one of his most evil acts by far, but there's also a more subtle maliciousness in his interactions with Brock thereafter. Whenever Walt visits the Cantillo home, he attempts to interact with the boy despite making him visibly uncomfortable - something that may be a result of Brock knowing that Walt hurt him, depending on how one interprets comments from Vince Gilligan. The showrunner said that Walt would have had to sneak into Brock's school to deliver the toxic substance, probably via a juice box. Gilligan explained:
The writers would always tell the story of the "Evil Juice Box Man." The way we worked it out on our timeline is he had just enough time to do it, but it would've been very tricky indeed. That's our inner story, the writers and I, for how it happened. It would've been very tricky timing, but he was a motivated individual at that point.
Harming a child and then continuing to taunt him with his insincere words is beyond simple deviancy.
Episode 5 from Breaking Bad's fifth season, "Dead Freight," ends with Todd Alquist firing at an innocent child, subsequently taking his life. The incident naturally proves to be traumatic for Jesse Pinkman. At first, Walter White also appears to have been negatively affected by the boy's demise, but his actions in the following episode give Pinkman reason to believe otherwise.
After a news broadcast about Drew Sharp's disappearance disturbs Jesse, Walt offers to finish the cleanup process while Jesse knocks off early. Pinkman lingers around long enough, however, to overhear Walt start to whistle as he works - clearly not as upset by the grisly moment as he was pretending to be. It's an important moment in both Jesse and the audience's ultimate realization that Walter White is a terrible person.
Walter White’s actions often put the lives of innocent people at risk - but rarely as directly as they do in "Face Off," the finale of Breaking Bad's fourth season. On the run from Gus Fring, Walt has suspicions that his house is being watched by would-be hitmen, so he decides to send in a decoy. He calls his neighbor, Becky Simmons, and asks her to check whether or not Walter Jr. left the stove on - and watches the action from down the street through a pair of binoculars.
The entirely unsuspecting Simmons wanders into the White home, only to have a close-call with two hitmen lying in wait. Ultimately, they decide to leave the premises rather than risk being spotted by someone other than their target - and Walt uses the opportunity to retrieve his money from the home - but at no point does he show the slightest bit of concern for his neighbor. As per usual, Walter White is only worried about himself.