The default application launcher that provides a click-through interface for finding and launching applications. Kickoff has a search facility, allowing you to type the name of the application or its description to find it. As of January 2017, last updated in December 2016..
Lancelot is a powerful application launcher which also allows launch menus to be placed on the panel. Lancelot provides search facilities, so if you know the name of the application you don't need to find your way around the menu. As of January 2017, last updated in March 2015..
KickoffMenu / KMenu is available from either the Add Widgets interface or by right-clicking on Kickoff and selecting "Switch to Classic menu style", this speedy and intuitive application launcher provides a classical hierarchical menu that is easily customized (via right click) to give quick access to various useful applications and services.
KRunner replaced the former "Run Command" dialog. KRunner offers a mix of task manager, desktop search, app launcher and CLI and provides a quick way to run applications or open documents among other things.