Apology can mean a formal justification or defense, such as:

• The prototype of such "apologies": The Apology of Socrates, as written down by Plato, see Apology (Plato)
• The Apology of Socrates, as written down by Xenophon, see Apology (Xenophon)
• Philipp Melanchthon's Apology of the Augsburg Confession
• François-René de Chateaubriand's Génie du christianisme
• Cardinal Newman's Apologia Pro Vita Sua