December 1 edit
Adelgar; Agericus of Verdun; Airy of Verdun; Algeric of Verdun; Edmund Campion; Saint Eligius; Simon of Cyrene;
December 2 edit
Abibon; Adamnan of Coldingham; Adrias & Paulina; Chromatius; John of Ruysbroeck;
December 3 edit
Abbo of Auxerre; Pope Abraham of Alexandria; Abran; Agapius, Seleucus and Mamas; Agricola; Francis Xavier;
December 4 edit
Ada; Adrechildis; Anno II, Archbishop of Cologne; John of Damascus; Saint Osmund; Peter Chrysologus;
December 5 edit
Saint Abercius; Birinus; Sabbas the Sanctified;
December 6 edit
Abraham of Kratia; Agatha; Saint Nicholas;
December 7 edit
Agatho; Ambrose; Pope Eutychian; Martyrs of Africa;
December 8 edit
Feast of the Immaculate Conception; Martyrs of Africa;
December 9 edit
Abibus of Samosata; Abracius; Abrax; Aemilianus; Aggai of Edessa; Aprax; Feast of the Immaculate Conception; Peter Fourier;
December 10 edit
Abundius; Pope Leo I;
December 11 edit
Aemilianus; Pope Damasus I; Daniel the Stylite; Pope Miltiades;
December 12 edit
Abra of Poitiers; Apra; Odile; Our Lady of Guadalupe; Vicelinus;
December 13 edit
December 14 edit
Abraham the Great of Kidunja; Abundius; Agnellus of Naples;
December 15 edit
Adelheidis; Mary di Rosa;
December 16 edit
Adelaide; Aggaeus; Agricola; Haggai; Martyrs of Africa;
December 17 edit
Shadrach, Meshach, and Abednego; Agatho;
December 18 edit
Adjutor; Afra; Frumentius;
December 19 edit
Adjutor; Adjutor; Adjutus of Portesan; Ajut; Pope Anastasius I; Ignatius of Antioch;
December 20 edit
Abraham of Armenia; Ignatius of Antioch;
December 21 edit
Addaeus; Thomas the Apostle;
December 22 edit
Abban of New Ross; Ago of Poitiers; Alexander of Cappadocia and Jerusalem; Saint Chrysogonus;
December 23 edit
Abassad; Agathopus;
December 24 edit
Achaicus; Achmed; Adela;
December 25 edit
Adalsindis; Martyrs of Achmin; Martyrs of Panopolis;
December 26 edit
Abadiu of Antinoe; Saint Stephen; Vincentia Lopez; Pope Zosimus;
December 27 edit
Saint Fabiola; John, Apostle and Evangelist;
December 28 edit
Abel; Massacre of the Innocents;
December 29 edit
Achatius; Adhanius & Astea; Aesculapius; Massacre of the Innocents; Peter the Venerable; Thomas Becket;
December 30 edit
Abraham the Writer; Commemoration of St. Mary the Virgin; Pope Dionysius;
December 31 edit
Aggaeus; Pope Sylvester I;