Daf Yomi 5b: Mutant Amoraim

We see on this daf that R Yochanan had an encounter with some toxic waste, such that his arm glowed enough to light up a room.

רבי אליעזר חלש
על לגביה רבי יוחנן
חזא דהוה קא גני בבית אפל
גלייה לדרעיה ונפל נהורא
חזייה דהוה קא בכי ר' אליעזר
א"ל אמאי קא בכית

Rabbi Eliezer became ill
Rabbi Yochanan came in to visit him
He saw that he was dwelling in a dark house
He exposed his arm and light fell from it.
He saw that Rabbi Eliezer was crying.
He asked him: Why are you crying...

Of course, he is not a mutant, but rather this is a sign of his elevated spirituality.

We see that Abaye's widow had similar mutant powers. In Ketubot 65a:

חומא דביתהו דאביי אתאי לקמיה דרבא
אמרה ליה פסוק לי מזוני
פסק לה
פסוק לי חמרא
א"ל ידענא ביה בנחמני דלא הוה שתי חמרא
אמרה ליה חיי דמר דהוי משקי ליה בשופרזי כי האי
בהדי דקא מחויא ליה איגלי דרעא
נפל נהורא בבי דינא
קם רבא על לביתיה תבעה לבת רב חסדא
אמרה ליה בת רב חסדא מאן הוי האידנא בבי דינא
אמר לה חומא דביתהו דאביי
נפקא אבתרה מחתא לה בקולפי דשידא עד דאפקה לה מכולי מחוזא
אמרה לה קטלת ליך תלתא ואתת למיקטל אחרינא

Homa, Abaye's wife, came to Rava {after Abaye's death}
She asked him, 'Grant me an allowance of food',
and he granted her.
'Grant me an allowance of wine'.
He said to her: I know that Nachmani {a name for Abaye} did not drink wine.
She said to him: By the life of the Master [I swear] that he gave me to drink from horns like this
As she was showing it to him her arm was uncovered
and a light shone upon the court.
Rava rose, went home and solicited R. Chisda's daughter. {to bed; she was his wife}
R. Chisda's daughter said: Who has been today at the court?
He said to her: Choma the wife of Abaye.
Thereupon she followed her, striking her with the straps of a chest {threatening to strike her} until she chased her out of all Machoza.
She said to her: You have already killed three {Abaye was her third husband who had passed away} and now you come to kill another!? {that is, she thought Abaye's widow was after her husband, Rava, as well}

Again, even though the accidental uncovering of her arm caused others {namely Rava} to be attracted such that he uncharacteristically visited his wife in the midde of the day, we see that she must have been a holy person so have this light shine from her arm.

{Note: this might be a good source for a tziut-related obligation to cover the arm, or elbows.}

We know of another who was able to light up the room. Moshe, in his later years, after bringing down the luchot, had light shining from his face, saith the pasuk, a topic I discussed on in this post on parshat Ki Tisa.

In Shemot 34:30-35:

ל וַיַּרְא אַהֲרֹן וְכָל-בְּנֵי יִשְׂרָאֵל, אֶת-מֹשֶׁה, וְהִנֵּה קָרַן, עוֹר פָּנָיו; וַיִּירְאוּ, מִגֶּשֶׁת אֵלָיו.	30 And when Aaron and all the children of Israel saw Moses, behold, the skin of his face sent forth beams; and they were afraid to come nigh him.
לא וַיִּקְרָא אֲלֵהֶם מֹשֶׁה, וַיָּשֻׁבוּ אֵלָיו אַהֲרֹן וְכָל-הַנְּשִׂאִים בָּעֵדָה; וַיְדַבֵּר מֹשֶׁה, אֲלֵהֶם.	31 And Moses called unto them; and Aaron and all the rulers of the congregation returned unto him; and Moses spoke to them.
לב וְאַחֲרֵי-כֵן נִגְּשׁוּ, כָּל-בְּנֵי יִשְׂרָאֵל; וַיְצַוֵּם--אֵת כָּל-אֲשֶׁר דִּבֶּר יְהוָה אִתּוֹ, בְּהַר סִינָי.	32 And afterward all the children of Israel came nigh, and he gave them in commandment all that the LORD had spoken with him in mount Sinai.
לג וַיְכַל מֹשֶׁה, מִדַּבֵּר אִתָּם; וַיִּתֵּן עַל-פָּנָיו, מַסְוֶה.	33 And when Moses had done speaking with them, he put a veil on his face.
לד וּבְבֹא מֹשֶׁה לִפְנֵי יְהוָה, לְדַבֵּר אִתּוֹ, יָסִיר אֶת-הַמַּסְוֶה, עַד-צֵאתוֹ; וְיָצָא, וְדִבֶּר אֶל-בְּנֵי יִשְׂרָאֵל, אֵת, אֲשֶׁר יְצֻוֶּה.	34 But when Moses went in before the LORD that He might speak with him, he took the veil off, until he came out; and he came out; and spoke unto the children of Israel that which he was commanded.
לה וְרָאוּ בְנֵי-יִשְׂרָאֵל, אֶת-פְּנֵי מֹשֶׁה, כִּי קָרַן, עוֹר פְּנֵי מֹשֶׁה; וְהֵשִׁיב מֹשֶׁה אֶת-הַמַּסְוֶה עַל-פָּנָיו, עַד-בֹּאוֹ לְדַבֵּר אִתּוֹ. {ס}	35 And the children of Israel saw the face of Moses, that the skin of Moses' face sent forth beams; and Moses put the veil back upon his face, until he went in to speak with Him. {S}

But the Midrash tells us he lit up the room from an even earlier age. As we see in parshat Shemot, in Shemot 2:2:

ב וַתַּהַר הָאִשָּׁה, וַתֵּלֶד בֵּן; וַתֵּרֶא אֹתוֹ כִּי-טוֹב הוּא, וַתִּצְפְּנֵהוּ שְׁלֹשָׁה יְרָחִים.

2 And the woman conceived, and bore a son; and when she saw him that he was a goodly child, she hid him three months.

The Midrash states that when Moshe was born, he filled the entire house with light. This is partly based on the כִּי-טוֹב, which is initially said with regard to light (Bereishit 1:4):

ד וַיַּרְא אֱלֹהִים אֶת-הָאוֹר, כִּי-טוֹב; וַיַּבְדֵּל אֱלֹהִים, בֵּין הָאוֹר וּבֵין הַחֹשֶׁךְ.

4 And God saw the light, that it was good; and God divided the light from the darkness.

but also likely has to do with interpreting the word כִּי hyper-literally as "because" rather than "that" or "how" in the second pasuk of Shemot. That is, וַתֵּרֶא אֹתוֹ, she saw him even though the house was dark only כִּי-טוֹב הוּא because he was tov, a reference to the fact that light shone from him.