As The Imitation of Christ is not a story, there aren't exactly characters. That's not to say there isn't something of a narrative and there aren't individuals present, but it's more loose than that.

First of all, the majority of the book is devotional in nature and more of a prescription for living a good, moral, Christian life. Hammerken writes some items in a spoken word narrative sense, reminiscent of many of the Psalms, where the character is the narrator himself; therefore, in much of the book, the characters are simply the Narrator and the Reader.

He does, however, incorporate a section, book 3, where Christ speaks directly to a Believer, and they exchange exhortations, thoughts, and questions in a dialogue of sorts. Christ explains the importance of many virtues and how to focus on eternal life and God the Father, and the believer inquires on how to improve while also praising God and Christ for their presence and for their good works. God the Father acts as an off-stage third character, being frequently referred to but never actually speaking or acting in the course of the dialogue. Additionally, the Holy Spirit is discussed as a character, a presence which will act as a guide.

Because Hammerken goes to great lengths discussing the Holy Sacrament, Communion, he spends a great deal of time outlining the duties and requirements of the clergy, specifically priests who are administering the sacrament. In this way, they act as something of another silent character, and they are addressed frequently throughout the section on the sacrament, where the author is compelling them to take certain actions, such as remaining pure and interceding for the laymen.

The majority of the book is not narrative in nature, so there aren't truly characters in the typical sense of the word, but there are separate parties who are addressed and who participate in the book. As a devotional, it instructs different individuals in an abstract sense.