Person

At times Tanakh switches from speaking in first or second person to third person (or vice versa) when it seems unwarranted, as there does not seem to be a switch in addressee. In many such cases,  commentators debate the verse's intent, questioning whether a new person is nonetheless being addressed¹ or if  it is simply "the way of the text" to switch person mid-verse. Several.of many examples follow:

• Bereshit 27:31– Esav tells his father, "יָקֻם אָבִי וְיֹאכַל מִצֵּיד בְּנוֹ בַּעֲבֻר תְּבָרְכַנִּי נַפְשֶׁךָ", beginning in third person and ending in second. In this case the third person formulation might be a sign of respect.
• Bereshit 49:4 – Yaakov rebukes Reuven, "כִּי עָלִיתָ מִשְׁכְּבֵי אָבִיךָ אָז חִלַּלְתָּ יְצוּעִי עָלָה", starting in second person (עָלִיתָ) but ending in third (עָלָה). According to Targum OnkelosBereshit 49:4About Targum Onkelos, despite the change in person, both clauses are speaking of Reuven's actions.²  ChizkuniBereshit 49:4About R. Chizkiyah b. Manoach, instead, suggests that Yaakov is addressing the second half of his words not to Reuven but to the rest of the tribes, to explain why Reuven was no longer deserving of the honors of the firstborn.³
• The Decalogue – The first two commandments of the Decalogue ("I am your God", "You shall have no other gods...") are spoken in first person, but the rest of the ten, speak of Hashem in third person.⁴ Ibn Ezra on Shemot 20:1 maintains that the switch in person is insignificant and Hashem spoke directly to the nation throughout the Decalogue, while R"Y KaraShemot 20:1About R. Yosef Bekhor Shor suggests that it indicates that only the first two statements were relayed directly by God to the people, while the rest were relayed by Moshe. For full discussion and the implications of the debate, see The Decalogue: Direct From Hashem or Via Moshe?
• Ibn Ezra Rut 4:4 – Boaz tells the potential redeemer of Ruth, ""אִם תִּגְאַל גְּאָל וְאִם לֹא יִגְאַל הַגִּידָה לִּי", beginning in second person, but mid-sentence switching to third person. See Ibn JanachYeshayahu 1:29Rut 4:3Rut 4:4Bereshit First Commentary 49:4Tehillim Second Commentary 81:17About R. Avraham ibn Ezra⁵ that despite the third person formulation, Boaz is speaking to the redeemer throughout and the switch in speaker is simply the way of the text. Alternatively, perhaps in the midst of his speech Boaz turned to the others in attendance and addressed them.
• Malakhi 2:15 – The verse switches from second to third person: וְנִשְׁמַרְתֶּם בְּרוּחֲכֶם וּבְאֵשֶׁת נְעוּרֶיךָ אַל יִבְגֹּד.  Compare RadakYeshayahu 1:29Yeshayahu 38:12Yeshayahu 42:20Yirmeyahu 11:16Yirmeyahu 30:8Yechezkel 5:15Yechezkel 28:22Malakhi 2:15About R. David Kimchi, that this is simply the way of the text, with RashiMalakhi 2:15About R. Shelomo Yitzchaki, who suggests that the final clause is truncated and should read as if written "אל יבגוד רוחך" (in which case the entire verse is really in second person).
• Other examples – Bereshit 49:9,⁶ Shemot 23:18-19,⁷ Shemuel I 19:42,⁸ Melakhim I 22:28,⁹ Yeshayahu 1:29,¹⁰ Yeshayahu 33:2,¹¹ Yeshayahu 38:12,¹² Yeshayahu 42:20,¹³ Yeshayahu 42:24,¹⁴ Yeshayahu 48:14,¹⁵ Yirmeyahu 11:16,¹⁶ Yirmeyahu 17:1,¹⁷ Yirmeyahu 22:24,¹⁸ Yirmeyahu 30:8,¹⁹ Yechezkel 5:15,²⁰ Yechezkel 28:22,²¹ Yechezkel 31:10,²² Mikhah 1:2,²³ Mikhah 7:19,²⁴ Tehillim 50:23,²⁵ Tehillim 68:36,²⁶ Tehillim 81:17,²⁷ Iyyov 17:10²⁸

Sometimes people refer to themselves in third person, by their name or title.²⁹  In some cases this might be a declaration of authority (as when a king refers to himself as such).

• Bereshit 4:23 – When speaking to his wives, Lemekh calls himself by name:"נְשֵׁי לֶמֶךְ הַאְזֵנָּה אִמְרָתִי" (rather than saying, "my wives").
• Shemot 20:2-6 – See discussion about the Decalogue above.
• Shemot 23:18-19 – Hashem opens by speaking in first person, but then refers to Himself in third.
• Shemot 24:1– Hashem speaks to Moshe and refers to Himself by name (in third person) "וְאֶל מֹשֶׁה אָמַר עֲלֵה אֶל י״י".  Cf. Rashbam that since the verse is not in first person one must assume that an angel is speaking.
• Tehillim 50:23 – Though the psalmist speaks through the voice of Hashem, it presents Hashem as speaking of Himself in third person:  "אַרְאֶנּוּ בְּיֵשַׁע אֱלֹהִים".  It is possible, though that here "אֱלֹהִים" is being used as a superlative, with the phrase meaning: "I will show him great salvation"
• Esther 8:8 – Though Achashverosh is speaking, he refers to Himself as "the king": "וְאַתֶּם כִּתְבוּ עַל הַיְּהוּדִים כַּטּוֹב בְּעֵינֵיכֶם בְּשֵׁם הַמֶּלֶךְ ".

The second person feminine conjugation is normally marked by the "תְּ" ending (as in: "שָׁכָבְתְּ" or "עָבַרְתָּ"). The archaic form of the same conjugation had a "י" at the end ("שָׁכַבְתִּי").³⁰ In several instances this older form is preserved in Tanakh, when a verse has a "קרי וכתיב", a word written one way but read another. See, for example, Yirmeyahu 2:33 (לִמַּ֖דְתְּ / למדתי), Yirmeyahu 3:4 (קָרָ֥את / קראתי), Yechezkel 16:43, 51 (זָכַרְתְּ/ זכרתי and עָשִׂית / עשיתי), Ruth 3:3 (וְיָרַדְתְּ / וירדתי), or 3:4 (וְשָׁכָבְתְּ / ושכבתי).³¹  There are also several verses in which commentators debate whether a verse should be understood as preserving this archaic form, or if the first person, perfect conjugation is implied:

• Yirmeyahu 2:20 – The verse reads, "כִּי מֵעוֹלָם שָׁבַרְתִּי עֻלֵּךְ נִתַּקְתִּי מוֹסְרוֹתַיִךְ". See the opinion in Shadal, that "שָׁבַרְתִּי" and "נִתַּקְתִּי" should be understood as a second person form, with Hashem telling the nations that they have always broken the yoke (of Torah).³² [Note: Shadal does not suggest that this relates to the archaic form, but instead that the "yud" is superfluous.] 
• Yirmeyahu 6:2 (דָּמִיתִי בַּת צִיּוֹן) – See Shadal that this might be the equivalent of the second person, feminine, meaning "you shall be silent".  [Here, too, Shadal does not suggest that this relates to the archaic form, but instead that the "yud" is superfluous.]
• Yechezkel 16:50 – See ShadalYechezkel 16:50About R. Shemuel David Luzzatto.
• Shofetim 5:7 – In Devorah's song after her victory over Sisera, she tells of how there was a lack of security in Israel "עַד שַׁקַּמְתִּי דְּבוֹרָה שַׁקַּמְתִּי אֵם בְּיִשְׂרָאֵל".  Bavli Pesachim 66b criticizes Devorah for praising herself, but M. Tzipor³³ has suggested that perhaps the word "שַׁקַּמְתִּי" should be understood as the archaic form of the second person feminine, "שקמת" (you rose). If so, the song is responsive, and contains certain lines said by the audience, who here praise Devorah.

Certain conjugations look identical leading to ambiguity in meaning.  For example, the future second person masculine and the future third person feminine have the same form, so without context "תלך" can mean either "you will go" or "She will go".  Similarly, certain forms of the third person singular passive construction might look like a first person future plural. Thus "נברא" can mean either "it was created" or "we will create". Though often a verse will provide enough details to determine which is referred to, in several cases a verse is ambiguous:

Second Person Masculine vs. Third Person Feminine

First Person Future Plural vs. Third Person Singular Passive

Miscellaneous