The Revered Elder
Nāyanāṟ (Tamil: 'the revered lord' / 'our Nāyaka [leader]') is used as an honorific for several figures in the tradition. In Śrī Vaiṣṇava usage, Nāyanāṟ most specifically refers to Azhagiya Maṇavāḷa Perumāḷ Nāyaṉār — the younger brother of Piḷḷai Lokācārya.
Azhagiya Maṇavāḷa Nāyaṉār
He was a highly accomplished Ācārya in his own right, a disciple of Nampiḷḷai's lineage, and the author of Ācārya Hṛdayam — one of the most celebrated and profound Śrī Vaiṣṇava granthams. Ācārya Hṛdayam (also called Azhagiya Maṇavāḷa Nāyaṉār Prabandham) explores the deeper inner meaning (svāpadeśa) of the Divya Prabandham.
The Two Brothers
The teaching lineage at Śrī Raṅgam in the 13th century was enriched by the presence of both brothers: Piḷḷai Lokācārya systematizing Teṅkalai doctrine in his Rahasya Granthams, and Nāyanāṟ revealing the esoteric dimensions of the Divya Prabandham in Ācārya Hṛdayam.