I have a requirement where I want to have a custom list view button with an ability to perform a mass custom action in the Lightning environment.
I do not see an option to add lightning quick-action on the list view.
Is there any way to have a custom list view button on a custom object?
Currently there is no way to directly call a lightning component from a list view button. My advice would be to build it using lightning out in a visualforce page. This will not only allow you to build it in lightning but it will also make it easy to transition it if and when they make it possible to link to lightning components from a list view button
Activity buttons and they are more like tabs in LEX and will stay in the Activities standard component - you should see it in the app builder:
Again - this is the Activities standard component - you cannot change it so you cannot remove the create new textbox and the add button.
Case Comments is a related object list - you can put it wherever you want with the app builder - just drag the Related List component and then select the object:
Best Answer
You can create a Visualforce page using the standard list controller, and define it as a list button.
Refer this link: Adding Custom List Buttons using Standard List Controllers
These display as expected in Lightning:
Don't forget the Custom Object must be Searchable in order to add your new button to the List View Search Layout.
You can then use Lightning for Visualforce (Lightning Out) to render a lightning component in your VF page if you're doing a primarily lightning component project.
Trailhead Module: Use Visualforce in Lightning Experience