Code:
Dim colorNames As String() = [Enum].GetNames(GetType(KnownColor))
For Each colorName As String In colorNames
Dim _knownColor As KnownColor = DirectCast([Enum].Parse(GetType(KnownColor), colorName), KnownColor)
If _knownColor > KnownColor.Transparent AndAlso _knownColor < KnownColor.ButtonFace Then
ComboBox1.Items.Add(colorName)
End If
Next