Henry has neck-length slicked back hair matched with a long straight beard that resembles an uppercase "W".
Taking into consideration his age, he has noticeable creases and wrinkles on his face accompanied by small, almost squinty eyes with thin eyebrows right above them. Usually, he is seen with a monocle on his left eye.
Being of an elderly age, Henry is a mature and noble person. This can be seen in his interview with the Forger family, he was calm and composed. Even at Eden Academy, when he teaches students, he observes and mentally criticizes the students. Although, he is a bit weird as seen with his constant obsession with "elegance".
Not much is known about Henry's upbringing, but it can be assumed he has a high social background of some sort.
Not much is known yet about Henry's capabilities.
Henderson has a deep respect for Loid, having personally acknowledged Loid's "elegance" and being deeply impressed by Loid's ideals. Loid's actions cause Henderson to completely rethink how he approaches being an educator. Because of Loid, Henderson has regained his old love for teaching.
- In each chapter that features a class taught by someone other than Henry, that person ends up calling in sick that day and Henry fills in for them. This first happens in Chapter 15 when the gym teacher is sick, and then again in Chapter 25 when the art teacher is sick.