Check if 'T' inherits or implements a class/interface

You can use constraints on the class.

MyClass<T> where T : Employee

Take a look at http://msdn.microsoft.com/en-us/library/d5x73970.aspx

If you want to check during compilation: Error if if T does NOT implement the desired interface/class, you can use the following constraint

public void MyRestrictedMethod<T>() where T : MyInterface1, MyInterface2, MySuperClass
{
    //Code of my method here, clean without any check for type constraints.
}

I hope that helps.

There is a Method called Type.IsAssignableFrom().

To check if T inherits/implements Employee:

typeof(Employee).IsAssignableFrom(typeof(T));

If you are targeting .NET Core, the method has moved to TypeInfo:

typeof(Employee).GetTypeInfo().IsAssignableFrom(typeof(T).Ge‌​tTypeInfo())

Note that if you want to constrain your type T to implement some interface or inherit from some class, you should go for @snajahi's answer, which uses compile-time checks for that and genereally resembles a better approach to this problem.