New Cast Member

To add somebody to the cast, search for the actor and select him/her from the drop down list. Next, please provide the name of the character played by the actor. Finish by clicking Ok. If you have person and role in the format 'person: role' or similar you can add them directly to the field 'person' and then click 'split'. In this case you can also add multiple persons and their roles at once if they are separated by line breaks.
You can also assign a cast member to a season and inherit him/her to all episodes. This way you don't have to add the actor to each episode. To do so, change to Knightfall > Season 2 (2019) and edit the cast there. Make sure, "inherit crew/cast" is activated.