The chords of the Major and Minor scales can be indicated by roman numerals.
Major chord: I, II, III, etc.
Minor chord: i, ii, iii, etc.
Augmented chord: I+, II+, III+, etc.
Diminished chord: vi°, vii°, etc.
Half-diminished chord: viiØ7, etc.
Extended chords: ii7, V9, V13, etc.
Altered tones or chords: #iv, ii#7
Chords of the Major Scale:
Chords of the Natural minor scale:
Chords of the Harmonic minor scale:
Chords of the Melodic minor scale (ascending):
Other examples: