I think most influential is pretty subjective and the range of purges meant pretty much everyone who -was- overly influential and famous got purged. And the remainder of the Communist party in the aftermath of Stalin's purges was absolutely subordinated to him (with the possible exception of Beria)

The closest I can think of would be someone like Anastas Mikoyan. If you look at Soviet Politburo membership list basically everyone on it from 1917-mid 1930s who wasn't firmly on Stalin's side all the way through got shot.