Despite the wide recognition of language teacher educators’ contributions in the field of Teaching English to Speakers of Other Languages (TESOL), research on language teacher educators has only picked up the pace in the last decade, shedding light on their cognition, practices, and identities in relation to various personal, interpersonal, and contextual factors. This article provides a systematic and critical review of 69 empirical studies on university-based TESOL teacher educators from 2010 and 2020. A methodological review was also conducted to analyze the different research approaches employed by previous researchers. A synthesis of the identified research led to four major themes, namely: (1) a general professional state (including responsibilities, challenges and quality), (2) professional engagement (including teaching, practicum supervision, and research and publishing), (3) cognition (including beliefs, knowledge, and expertise), as well as (4) continuous learning and identity development. Through a critical discussion of the themes, the review argues against the implicit yet powerful discourse that characterizes language teacher educators as ‘supermen/superwomen’ and emphasizes the need to humanize them as whole people by recognizing their unique strengths and struggles as well as diverse learning needs. The review also proposes a new research agenda to stimulate and deepen future investigations on language teacher educators in TESOL.