Marvel's What If..? Episode 6 has been a wild ride for everyone with the story of Killmonger rescuing Tony Stark from the moment he was supposed to struggle and without such, he wouldn't become Iron Man. More than that, it showed how Eric became ruthless for his goal: be the next Black Panther, that he killed a lot of people to do so, even heroes died in the process. Who are those?
Warning! This portion may contain spoilers for Marvel's What If..?. Read at your own risk!
The Heroes Who Died in Marvel's What If..? Episode 6
In What If.. Killmonger Rescued Tony Stark, it did not focus much on the latter but more on Erik who plotted everything from the start to become the next Black Panther. The episode started with Stark in Afghanistan and Killmonger saved him from one of the bombs from his company, Stark Industries, and later, Erik revealed that it was all planned he would be there because Obadiah Stane or Iron Monger instructed him to kill Stark.
When Stane was removed as COO, Erik was offered by Stark to be his right-hand man and they built what looks like sentinels made out of vibranium, like Stark described, the biggest Gundam there would be, and when they wanted more of the said metal, they met with Ulysses Klaue but such turned out to be a bust when T'Challa arrived.
This is when the deaths happened.
He died in the bust that happened as he was the one who met with Ulysses Klaue and he was killed by Killmonger when he double-crossed them. In this timeline, he never became War Machine because Stark never got to build his own suit and that was where he was patterned into. He was just a member of the Army, a liaison for Stark Industries.
T'Challa/ Black Panther
Surprised to see him again? The third outing of T'Challa on What If..? made it the briefest but in this one, he died in the hands of Killmonger who took his glove and used it to kill him. Wakanda even had him a funeral and with no heir, it opened the door for Erik.
Tony Stark/ Iron Man
Once he figured it all out, Stark sure was a genius one as he managed to record it all. He found out that Killmonger killed his best friend, Rhodes, and all the others who were there in the bust. Stark did not go down without the fight, he unleashed the sentinel-like robot to Erik but since he carried a vibranium spear, it was easy to take it down, so did Stark who died afterward from the same spear.
Marvel's What If..? Episode 6 is now streaming on Disney Plus.