Monsignor (/ mɒnˈsiːnjər /) is an honorific form of address for those members of the clergy of the Catholic Church including bishops, honorary prelates and canons. In some cases, these ecclesiastical honorific titles derive from the pope, but in other cases it is simply a customary or honorary style belonging to a prelate or honorary prelate. These are granted to individuals who have rendered valuable service to the Church, or who provide some special function in Church governance, or who are members of bodies such as certain chapters. The title is never bestowed on those classified as religious in Catholicism. Although in some languages the word is used as a form of address for bishops, which is indeed its primary use in those languages, this is not customary in English. Monsignor is the apocopic form of the Italian monsignore, from the French mon seigneur, meaning "my lord". It is abbreviated Mgr, Msgr, or Mons.

Answer this question: what is a monsignor in the roman catholic church? Let's give stream of consciousness first:
To answer the above question, the relevant sentence is: Monsignor (/ mɒnˈsiːnjər /) is an honorific form of address for those members of the clergy of the Catholic Church including bishops, honorary prelates and canons.
So, the final answer is bishops , honorary prelates and canons.