Without allowing for any repeats…
TPM - Pernilla August as Schmi Skywalker
AOTC - Christopher Lee as Count Dooku
ROTS - Ian McDiarmis as Emperor Sheev ‘Darth Sidious’ Frank Palpatine
ANH - Alec Guiness as Ben Kenobi
ESB - Frank Oz as Yoda
ROTJ - Sebastian Shaw as Anakin Skywalker (because McDiarmid was already picked)
TFA - Harrison Ford as Han Solo
TLJ - Mark Hamill as Luke Skywalker (Carrie Fischer honorable mention)