Bishops have them, as well as many popes. Religious orders have mottos, as well as individuals. Spiritual mottos may be in Latin or they may be in the language that a person speaks. Often the mottos are incorporated into a coat of arms of a pope or bishop. For example the spiritual motto of Cardinal George (of the Archdiocese of Chicago) is "Christo Gloria in Ecclesia" (To Christ be glory in the Church), which was inspired by Hebrews 13:20.
Pope John Paul II used "Totus Tuus" as his motto----simply put "Totally Yours" in his dedication to the Blessed Mother.