Have there been any cases of the Stigmata appearing to someone who is outside of Catholicism, yet still a member of Christianity? Such as a member of a Protestant denomination or sect of Eastern or Coptic Orthodoxy?
The only non-Catholic Christian I have heard who MAY have received the stigmata was St. Gregory Palamas who was Eastern Orthodox. This is HIGHLY disputed. The English translation of the Lenten Synaxarion APPEARS to say he was "adorned with the wounds of Christ" (Lenten Synaxarion - Sunday of St. Gregory Palamas)
However, no Eastern Orthodox authority interprets it this way. However, Byzantine Catholics do.