Gundam doesn't necessarily kill all their characters-most of the main cast survived in the original Gundam; ZETA however did kill off pretty much all the supporting cast apart from Haman, Camille was left in a semi-catatonic state, and Char was missing.
ZZ didn't really kill off anybody except Hayato, the original Ple, a few of the minor supporting characters (an Anaheim engineer and one of the Moon Moon princesses) and the villains. There was a fake-out death with the sister but that was it.
Char pretty much killed off most of the cast (Including Z/ZZ's Astonage) except for Bright, his son, and Char's second in command I think.
The 0080 OAV of course kind of continued that tradition with it's infamous death.
A lot of 0083's cast made it but it was kind of bittersweet since many of them joined the Titans (and were possibly killed during the Gryps war) and apparently Snynapse died offscreen.
Still haven't seen Victory but I heard that's pretty rough.