SharePoint is a great tool to collaborate and track document changes. 

But, have you ever had the requirement, that a form should be submitted "anonymously"?
Some customers know the princip of inboxes, where you can place a complaint anonymously.

Since this is a bit "not featured by design" in SharePoint, I would like to share my solution approach.
(There are others, as you can read here: Anonymous Form Submission but in my case, I don't want to delete submitted items.)

First, I create a new Site-Workflow.
For this scenario, I need two variables. One is for the complaint-message and one is an optional textfield, where you could enter your name, if you like.

(Please note: "Show on start form")

Secondly, I edit the start form with Nintex Forms. The fields are connected to the corresponding variable.

Thirdly, I insert two Workflow Actions. The Action Set is needed to run all child actions using the credentials of the user who published the workflow.

And that's it. In my case, I use the Nintex "Start Site Workflow"-Webpart to embed the form. All submitted items will be created by the account who published the workflow. So be careful not to use your personal account.