The concept of the 1שד יהודי is introduced by Rebbe Nachman in Likutei Moharan 12:1
(Source from Sefaria.org)
מַה שֶּׁאָנוּ רוֹאִים, שֶׁעַל־פִּי הָרֹב הַלּוֹמְדִים חוֹלְקִים עַל הַצַּדִּיקִים, וְדוֹבְרִים עַל הַצַּדִּיק עָתָק בְּגַאֲוָה וָבוּז, זֶהוּ מְכֻוָּן גָּדוֹל מֵאֵת הַשֵּׁם יִתְבָּרַךְ. כִּי יֵשׁ בְּחִינַת יַעֲקֹב וְלָבָן; יַעֲקֹב הוּא הַצַּדִּיק, הַמְחַדֵּשׁ חִדּוּשִׁין דְּאוֹרַיְתָא וְלוֹמֵד תּוֹרָתוֹ לִשְׁמָהּ, וְטוּבוֹ גָּנוּז וְשָׁמוּר וְצָפוּן לֶעָתִיד, כְּמוֹ שֶׁאָמְרוּ רַבּוֹתֵינוּ זִכְרוֹנָם לִבְרָכָה: לְמָחָר לְקַבֵּל שְׂכָרָם (עירובין כב.); וְעַל שֵׁם שֶׁשְּׂכָרוֹ לְבַסּוֹף, עַל שֵׁם זֶה נִקְרָא יַעֲקֹב, לְשׁוֹן עָקֵב וָסוֹף, שְׂכָרוֹ לְבַסּוֹף. וְלָבָן הוּא תַּלְמִיד־חָכָם שֵׁד יְהוּדִי, שֶׁתּוֹרָתוֹ לְהִתְיַהֵר וּלְקַנְטֵר, וְתַלְמִיד־חָכָם כָּזֶה נְבֵלָה טוֹבָה הֵימֶנּוּ (מ"ר ויקרא א, עיין מתנות כהונה):
That which we see among most of the learned who go against the Tzaddikim and speak about the Tzaddik wantonly with arrogance and scorn, is specifically planned from G-d. For there is the relation of Yaakov and Lavan; Yaakov is a Tzaddik who creates original (Torah) ideas and studies the Torah for its own sake and his reward is stored, guarded and kept for the future, as our sages of blessed memory state: "The next day they will claim their reward" 2 (Eiruvin 22). Because his reward is in the end he is thus called "Yaakov", a language of delay and end, his reward is for the end. As for Lavan, he is a wise scholar שד יהודי(?), whose Torah (study) is done to glorify himself and to provoke, and a dead animal is better than a wise scholar like this.
Was there anyone in particular Rebbe Nachman is speaking about when referring to the שד יהודי? Or is it to be thought strictly a concept developed?
1 The English translation of the Likutei Moharan (Put out by the Breslov Research institute) translates this as "Scholar Demon"
2 i.e. in the world to come