In Greece: Elder Joseph the Cave-Dweller. By all accounts, he started commemorating Athenagoras in 1950. He had a very negative reaction to the 1950 encyclical issued by Metropolitan Chrysostom of Florina, which stated that the New Calendarist State Church was schismatic and devoid of grace. Some people argue that he never resumed commemorating and that he only left the Florinite synod, isolating his synodia from all the other zealots on Mt. Athos due to the infighting between the Matthewites and Florinites. Some people argue that even if he did start commemorating again, he was still a saint. For me, I look at the fruits, and the fact is that all of his disciples became abbots of major Athonite monasteries in the 1970s (Elder Ephraim, Elder Joseph, Elder Haralambos). For me, Elder Joseph doesn't make the cut as a True Orthodox elder.
In Bulgaria: Archbishop Seraphim Sobolev. A disciple of Saint Theophan of Poltava and a spiritual father to Archbishop Averky of Syracuse (Archbishop Averky even wore his hair like Archbishop Seraphim). From what I've read, his relationship with Archbishop Theophan became strained in the 1930s. I'm not exactly sure why. He was widely loved within his diocese in Bulgaria, and all of the Bulgarian Old Calendarists are in some way "descended" from him, as he was the spiritual father of some of their first leaders. They glorified him as a saint in 2002, I believe. However, he ended up joining the MP in 1945 and started serving the divine liturgy at the local MP church at the Soviet embassy. He travelled to Russia in 1948 for the Council of Moscow, which anathematized ecumenism. This council seems to have occurred largely due to his own efforts. He reposed in 1950. This one is more difficult for me, since he left a lot of excellent essays which criticized the heresies of Sophianism, ecumenism, and the New Calendar. But if everyone agrees that MP fell into schism in 1927 after Metropolitan Sergius' declaration of loyalty to the Soviet Union, then I don't see how anyone can argue that Archbishop Seraphim didn't enter into schism by leaving the ROCOR and joining the MP in 1945.
Serbia: Saint Justin of Celije. By all accounts, he stopped commemorating Patriarch German in 1971 and refused to commemorate him until his repose in 1979. He still commemorated his local bishop, Jovan Velimirovic (nephew of Saint Nikolai Velimirovic).
Georgia: Elder Gabriel Urgebadze. Gained notoriety for burning a portrait of Lenin at a Soviet parade in 1965. He was subsequently imprisoned and tortured by Soviet authorities. He seems to have been a member of the Catacomb Church in his earlier days, but he eventually agreed to come under the protection of Patriarch (then Metropolitan) Ilia. A lot of True Orthodox in Georgia still venerate him today.