yodas master? sith emperor?

hi i was wondering who was yoda's master? and how many apprentice's has yoda had? and also who is the sith emperor and why are people saying hes so special?

Originally posted by coool121212
hi i was wondering who was yoda's master? and how many apprentice's has yoda had? and also who is the sith emperor and why are people saying hes so special?

Sith Emperor

i forgot to ask, are they also cannon?

Have a look.