Determining the least popular MBTI (Myers-Briggs Type Indicator) type is a subjective matter as popularity can vary depending on various factors such as cultural, societal, and personal preferences. However, based on general observations and anecdotal evidence, the INFJ (Introverted, Intuitive, Feeling, Judging) type is often considered one of the least common and therefore potentially the least popular.

1. Rarity: INFJs are estimated to make up only about 1-3% of the population, making them one of the rarest types. This rarity can contribute to their perceived lack of popularity as they may not be as commonly encountered or understood by others.

2. Complexity: INFJs are known for their complex and multifaceted nature. They possess a unique blend of traits that can be challenging to comprehend for those who are not familiar with their inner workings. This complexity can sometimes make it difficult for others to connect with or relate to INFJs, leading to a potential lack of popularity.

3. Misunderstandings: INFJs often have a deep need for authenticity, meaning, and connection. They tend to prioritize emotional depth and understanding, which can be misunderstood or undervalued by individuals who prioritize more practical or logical aspects of life. This can lead to INFJs feeling misunderstood or isolated, potentially contributing to their perceived lack of popularity.

4. Introversion: INFJs are predominantly introverted, meaning they gain energy from spending time alone and may find social interactions draining. This preference for solitude can sometimes make it harder for INFJs to engage in social situations or actively seek popularity, further contributing to their potential lack of popularity.

5. Elusiveness: INFJs are known for their private and reserved nature. They often keep their thoughts, emotions, and inner world hidden from others, making it challenging for people to truly understand them. This elusiveness can create a sense of mystery around INFJs, but it can also make it harder for others to connect with them, potentially leading to a lower level of popularity.

It is important to note that popularity is a subjective concept, and being less popular does not diminish the value or worth of any MBTI type. Each type brings unique strengths and perspectives to the world, and popularity should not be the sole measure of an individual's worth or contribution.