Magnus Maximus is mentioned in a number of ancient and Medieval sources.

• Ammianus Marcellinus Rerum Gestarum Libri Qui Supersunt XXXI.4.9
• Geoffrey of Monmouth Histories of the Kings of Britain V.5-6
• Gildas De Excidio et Conquestu Britanniae II.13-14
• 'Nennius' Historia Brittonum 27; 29
• Orosius Historium adversum paganos VII.34
• Pacatus Panegyricus Latini Pacati Deprani Dictus Theodosio
• Prosper (Tiro) of Aquitaine Chronicon 384; 388
• Socrates Scholasticus Historia Ecclesiastica V.8; V.11
• Sozomen Historia Ecclesiastica VII.13
• Sulpicius Severus Dialogi II.6;III.11,13
• Sulpicius Severus Historia Sacra II.49-51
• Sulpicius Severus Vita Sancti Martini XX
• Trioedd Ynys Prydein (The Welsh Triads)
• Zosimus Historia Nova