What is the honorific title of Laozi as a Taoist deity?

The honorific title of Laozi as a Taoist deity is Taishang Laojun. The name 太上老君 is commonly translated as “Supreme Old Lord” or “Most Venerable Lord Lao.”

In religious Taoism, Taishang Laojun is the deified form or manifestation of Laozi, the sage traditionally credited with the Daodejing. He is identified with Daode Tianzun, the Celestial Worthy of the Way and Its Virtue, and occupies the Taiqing position within the Three Pure Ones, Taoism’s highest divine grouping.

The religious identity developed beyond the historical or semi-legendary philosopher. By the Later Han period, Laozi was being treated as a divine manifestation of the Dao, and later Taoist traditions described Taishang Laojun as appearing in different incarnations to teach humanity. Tang rulers also honored Laozi with imperial titles and promoted his ancestral importance.

Tianzun alone is not the specific answer: it means “Celestial Worthy” and appears in several divine titles. Lingbao Tianzun and Yuanshi Tianzun are the other two members of the Three Pure Ones.