Tàixián 太賢 (also written 大賢; Korean: Taehydon / Daehyeon; fl. mid-8th century CE) was a major Silla Korean Yogācāra scholar-monk and commentator, known by the soubriquet Qīngqiū shāmén 青丘沙門 (“Monk of the Blue Hills,” i.e., Korea). He traveled to Tang China and studied Yogācāra at Xīmíng sì 西明寺 under Dàozhèng 道證, a disciple of Xuánzàng 玄奘 (玄奘). He was extraordinarily prolific; in 753 CE he conducted merit recitations in the Silla royal palace at the behest of King Jǐngdé 景德王 (r. 742–765) for rain-making. His subsequent fate is unknown.
He wrote more than forty works, a number of which are preserved in the Taishō Tripiṭaka: the Dàchéng qǐxìn lùn nèiyì lüètànjì 大乘起信論內義略探記 (T1849), the Běnyuàn Yàoshī jīng gǔjī 本願藥師經古迹 (T1770) — an important commentary on the Dharmagupta (KR6i0047, T449) and Xuánzàng (KR6i0048, T450) translations of the Bhaiṣajyaguru-sūtra — the Fànwǎng jīng gǔjī jì 梵網經古迹記 (T1815), the Púsà jiè běn zōngyào 菩薩戒本宗要 (T1906), and the Chéngyùshí lùn xuéjì 成唯識論學記 (X0818).
Tàixián returned to Silla and became the leading transmitter of the Cí’ēn 慈恩 (Yogācāra) school in Korea, earning the epithet “sea-east Yoga patriarch” (Hǎidōng Yúgā zǔ 海東瑜伽祖). His Yàoshī jīng gǔjī (T1770) is particularly valuable for reconstructing the transmission history of the Bhaiṣajyaguru-sūtra.