Isaiah was famously heralded by the church fathers (originally Jerome?) as "the fifth Evangelist." If there's room for another at the table, I propose we give the honor to Zechariah. Having never read the book start-to-finish before, in doing so the last couple of weeks I was repeatedly struck by how deeply interwoven it is into the canonical Gospels; along with Second Isaiah and the Psalms, it is an ineliminable feature of the Evangelists' depiction of Jesus's person, teachings, ministry, actions, and passion. Tug on that thread, and the texts unravel. Given its importance, I wonder—because I don't know—whether and to what extent the fathers and medievals read and commented on Zechariah, or whether, for whatever reason, it slipped by the wayside. Given its non-linear and non-systematic character, its apocalyptic and sometimes violent imagery, and its simultaneous emphasis on contemporaneous political events as well as the coming eschatological future, perhaps it was less immediately conducive to the sort of readings they would have been interested in undertaking.
But, wow, it is a powerhouse of figural christological exegesis. It's basically necessary pretext, historically, literarily, and theologically, for understanding the Gospels' presentation of Jesus. It's all there: Jerusalem (1:14-17; 8:3), exile (passim), YHWH's return (1:16; 8:3; 9:14), Israel's renewed election (2:12), the divine presence at the temple (2:5; 8:3; 9:8), a second exodus (14:16-19), the forgiveness of sins (3:9; 13:1), the Lord's rebuke of Satan (3:2), the eschatological gathering of all nations (passim), a priest-king named Joshua (6:11-13), the capstone (4:10), the anointed (4:14), the blood of the covenant (9:11), the Spirit's power and outpouring (4:6; 7:12; 12:10), grabbing a Jew by the hem of his robe (8:23), Israel's salvation (9:16), Israel's king at once human (9:9) and divine (14:9), 30 pieces of silver (11:12), the house of David (12:8), a cleansing fountain in Jerusalem (13:1), Jerusalem looking on him whom they have pierced (12:10), the shepherd struck and the sheep scattering (13:7), YHWH's feet standing on the Mount of Olives (14:4), the coming of YHWH with his saints (14:5), the day of darkness that is the first evening of the new creation (14:6-7), the singular sovereignty of the name of YHWH (14:9), the nations coming to worship this self-same king (14:16)—and so on.
I realize I'm not the first one to note this. (I'm vaguely aware that Wright, whose corpus I am making my way through as we speak, has made Zechariah central to his proposal about the historical Jesus's self-understanding.) But it's incredible nonetheless, both at a literary-historical level and, especially, in its implications for Christian theological interpretation of the Evangelists proper and of this unique proto-Evangelist.