| oceanBlue | Graphics.Color.Standard.RAL |
| ochreBrown | Graphics.Color.Standard.RAL |
| ochreYellow | Graphics.Color.Standard.RAL |
| OKLAB | |
| 1 (Type/Class) | Graphics.Color.Space.OKLAB |
| 2 (Data Constructor) | Graphics.Color.Space.OKLAB |
| OKLCH | |
| 1 (Type/Class) | Graphics.Color.Space.OKLAB.LCH |
| 2 (Data Constructor) | Graphics.Color.Space.OKLAB.LCH |
| oldLace | Graphics.Color.Standard.SVG |
| olive | Graphics.Color.Standard.SVG |
| oliveBrown | Graphics.Color.Standard.RAL |
| oliveDrab | |
| 1 (Function) | Graphics.Color.Standard.RAL |
| 2 (Function) | Graphics.Color.Standard.SVG |
| oliveGreen | Graphics.Color.Standard.RAL |
| oliveGrey | Graphics.Color.Standard.RAL |
| oliveYellow | Graphics.Color.Standard.RAL |
| one | Graphics.Color.Algebra.Binary, Graphics.Color.Model, Graphics.Color.Space.RGB.Alternative, Graphics.Color.Space.RGB, Graphics.Color.Space, Graphics.Pixel, Graphics.Pixel.ColorSpace |
| opalGreen | Graphics.Color.Standard.RAL |
| Opaque | Graphics.Color.Model, Graphics.Color.Space.RGB.Alternative, Graphics.Color.Space.RGB, Graphics.Color.Space, Graphics.Pixel, Graphics.Pixel.ColorSpace |
| orange | Graphics.Color.Standard.SVG |
| orangeBrown | Graphics.Color.Standard.RAL |
| orangeRed | Graphics.Color.Standard.SVG |
| orchid | Graphics.Color.Standard.SVG |
| orientRed | Graphics.Color.Standard.RAL |
| oxideRed | Graphics.Color.Standard.RAL |
| oysterWhite | Graphics.Color.Standard.RAL |