That is the public servants who uphold the best of the public service ethos. Part of that is to work for the public good without expecting great admiration or fame. In the UK, the Seven Principles of Public Life (also known as the Nolan Principles) are a good start. Often mentioned when things go wrong, they are a distillation of what’s expected or, at least, hoped for when encountering a public servant.
I have known people who have demonstrated, in their every day working lives the best of these principles, and more. To balance this finding, I have known people for whom any of these seven would have been a struggle.
Prefect people, if such a term can be used, are not common place. Even they have off days, when they stray from the path that they have set themselves.
Having done a fair number of audits of organisations over the years, the message to take is that great public service is often not what’s done when someone is looking, it’s what’s done when no one is looking.
John Vincent 
Useful post