Marvel's Secret Invasion became one of the comic book giant's most successful storylines. The series was filled with triumph and tragedy as several major characters were killed during Secret Invasion and not resurrected. Secret Invasion has had two variations, with the original storyline starting in 1984 and a reboot released in 2015.
Source:https://www.cbr.com/secret-invasion-marvel-comics-most-important-character-deaths/