Is it best practice to have all information pass through the MODEL to the CONTROLLER? 

For example, I have a controller named "Apps" and a model named "App". I want to show a form with a list of users, which is in the "Users" class in the libraries folder. Can I simply request the list of users from the "Users" class directly from the CONTROLLER or is it best to first go through the MODEL and then to the CONTROLLER?

TIA