Apps that stay in Dock when closed

CTRL- or RIGHT-click on the Dock icon for an app. If you check the Keep in Dock item from the Options sub-menu, then the icon remains in the Dock even after quitting the app. While the app is running there will be a small black triangle under the icon to show it is currently running.

There is a new feature in Dock that show recent open apps. Go to Apple Menu, System Preferences, Dock and uncheck Show recent applications in Dock.

In Mojave, uncheck "Show recent applications in Dock" in System Preferences > Dock.

Pitiger wrote:

My question is not about recent applications.

In that case the only Apps that would stay in the Dock are Apple apps or apps that have a preference setting to add themselves to the Dock when launched. Do you have any apps in mind?

Good to hear. Of course if you removed an app from the Dock by using "Remove from Dock" it should not remain in the Dock unless as I mentioned it has its own preference.

Thank you dialabrain, the recent applications was the issue for me - even apps that were manually added to the dock were being duplicated there. Deselecting the option fixed it.

You're welcome.