The panegyric of Constantine the Great delivered by Eusebius of Caesaria established a new convention of depicting the ideal emperor rather than the actual.
The Christian basilikoi logoi dropped references to good fortune (tyche) in favour of piety.
[1] The delivery of a basilikos logos could be used as an occasion to subtly advise the emperor, becoming a sort of "mirror of princes".
The surviving biography of the Empress Theodora (9th century) may originate in a basilikos logos addressed to her during her regency.
[2] John the Oxite wrote and presumably delivered an unconventional logos that was highly critical of the policies of Alexios I Komnenos (11th century).