Spared Z Fighter

Spared Z Fighter is the event in The Raditz sub-Saga that alters everything in the canon universe because it is the first saga which precedes Vegeta's and The SSJ sub-sagas. EVERY one of Goku's allies are Z Fighters to a degree. Goku is able to spare his brother's life without having to die himself. Bardock and Gine are revived. This goes in depth with Raditz's backstory of the betrayal he went through under Vegeta and Nappa. The alternate timeline had Kakarot not hit his head that Raditz unknowingly mentions is seen for dramatic irony where Kakarot is picked up by Raditz's alternate counterpart (having just slayed Piccolo) who helps him hunt down the Z Fighter Earthling's alternate selves. Raditz informs him to prepare the planet to be sold, assisting the slightly weaker Kakarot in destroying all it's inhabitants. The Bardock in this world is dead for real, having had these alternate visions. Krillin is the first to die when Kakarot was about to spare him, then Master Roshi. Raditz comes up with a plan for Kakarot to usurp Prince Vegeta. Yamcha is killed by Nappa's Saibamen before he could see them. Chiaotzu self-destructs, Tien dies. Vegeta finishes off Yajirobe. It's a foreshadowing of events to come long after these high-class Saiyans have settled down on Earth.