I found similar questions and answers for Python and Javascript, but not for C# or any other WinRT compatible language.
The reason I think I need it, is because I\'
I recommend using System.Net.WebUtility.HtmlDecode and NOT HttpUtility.HtmlDecode.
This is due to the fact that the System.Web reference does not exist in Winforms/WPF/Console applications and you can get the exact same result using this class (which is already added as a reference in all those projects).
Usage:
string s = System.Net.WebUtility.HtmlDecode("é"); // Returns é