Learner variables, also known as individual difference (ID) variables, are individual characteristics of learners of a foreign/second language (L2) that influence L2 learning processes and outcomes. Learner (or ID) variables that are commonly used in L2 research are, for example, age, anxiety, aptitude, attitude, beliefs, cognitive abilities, gender, language background, learning strategies, learning styles, motivation, personality traits (e.g. extroversion/introversion), proficiency, working memory and willingness to communicate. In digital game-based language learning and teaching (DGBLLT), an area of research within the broad field of computer-assisted language learning (CALL) research, it is always relevant to consider learners’ informal L2 learning outside the walls of educational institutions, that is, their extramural engagement in activities such as playing digital games and watching streamed media in the target language, as this learner variable complements any formal learning. It can be noted that informal L2 learning often comprises learners’ use of digital technology. Access to technology is a typical socioeconomic status (SES) learner variable connected with the so-called digital divide. In DGBLLT as well as in CALL research, writing is clearly most researched when it comes to various L2 proficiency variables. In this entry, the concept of learner variable and associated concepts/variables are defined. Research findings are summarized along with an attempt at identifying trends and research gaps related to learner variables in DGBLLT. Finally, suggestions for future research are provided.