Many occasions? That's a bit unfair, in Classic who we only have:
Sarah Kingdom (I haven't seen/heard it, but acknowledge her sacrifice)
Adric
Adric's Brother (And any others of his gang that might have died), if you want to count it (He was saved from certain death, and pirated the ship, before he ended up dying after the Hijacked trip)
In NuWho we have
DoctorDonna should be considered, although Donna lived, she stayed the same selfish shrew she started as, and probably got worse, considering she became
Nouveau Riche and the Donna who became DoctorDonna died, just as Tuvix did
Astrid never traveled
Jack got immortality, but, as we were told in Classic Who it becomes a curse, and he became Undead/unable to die
Rory Pond-Williams who died numerous times, but, it never stuck
Amy Pond-Williams (Amy who waited was erased, Ganger Amy and Manhattan Angels Amy), but that never stuck
Melody Pond-Williams transferred into The Library World, and from the Doctor's perspective she never traveled)
Did I miss anyone? Based Upon this list, I'm not sure I'd credit your "many" accusation with as many as 4.
