I've never heard that Superman had a specific motto, per se (like "Not in the face, not in the face!), but a couple of his most famous phrases are "Great Krypton!" and "Up, Up and Away!" which he says as he zooms off.
truth,justice and the american way
Supermans tights are red.
Fictional.
Krypton
Darksied
Steel
Metallo
justin bieber
The same as supermans
Clark Kent.
Planet of Krypton
Supermans birthplace
by supermans fighting