Hiding NPCs from Players

Hi all! I've started DMing with roll20 a few weeks ago. I wanted to add character sheets for NPCs (and monsters), but don't want my PCs to see them at all - not even that they exist! Is this the default state? If not, how can I do it? Thanks.

Hi Miel! This is the default state. Players can only see things in their journals that they have explicitly been given control over. You can test this by creating a   Dummy Account  and logging in with that. If you don't want them to see something that is on the map, you can place that token on the GM layer, and it will be hidden from them; even it's presence on the turn tracker will become invisible.

Thanks!