On the Majel Barrett side of things, Memory Alpha lists all her appearances.
She played Christine Chapel 27 times between TOS and the movies,
Lwaxana Troi 9 times between TNG and DS9
A Federation computer voice 243 times (15 episodes of TOS, 5 of TAS, 97 of TNG, 23 in DS9, 96 in VOY, 2 in ENT and 5 times in movies).
She did the “Previously on…” narration 23 times between TNG, DS9 and VOY.
She did the voice of Suspiria in the VOY episode Cold Fire
She played at least 15 different characters in TAS, providing voices in all 22 episodes.
So that’s a total of 325 appearances in total.
By comparison Michael Dorn plays Worf 274 times between TNG, DS9 and the movies, as well as Colonel Worf in Star Tek VI. They don’t list any times he did the “previously on…”
So Michael Dorn played Worf more times than Barrett played any one role including computer voices, but Barrett has been in more episodes.