St. Lawrence is celebrated as the "Proto-Deacon of the Roman Church," indicated by the Vatican biography written about him.
What is a "proto-deacon"?
Originally this title was given to the "chief" or "first" deacon in the Church of Rome. Fr. Francesco Moraglia, in his biography of St. Lawrence, notes that, "Sixtus was raised to the Chair of Peter and began a pontificate that would last for less than a year. Without hesitation, he desired to have Lawrence, his friend and disciple, at his side so as to entrust to him the important office of proto-deacon."
The proto-deacon would be among the closest clerics to the Bishop of Rome, an ordained deacon who would serve the pope by managing various tasks. St. Lawrence was put in charge of the material goods of the Church and to distribute them to the poor and needy.
Many Eastern Christians (Byzantine and Orthodox) still retain this title in reference to a senior deacon.
Eventually this title of proto-deacon was given to a cardinal in Rome, and currently the Senior Cardinal Deacon in Rome is given the task of announcing the name of the next pope after a conclave.