In addition to the fingerprint scanner, the Samsung Galaxy S6 has all of the basic lock screen options that other Android phones have: swipe, pattern, PIN, and password. There also just happens to be a secret sixth option called "Direction lock" that protects the device with a series of customizable directional swipes—only it's hidden in an unsuspecting settings menu.
You would assume that this feature would be in the same place as your other lock screen security options, but it's actually not. In order to enable directional swipes, you need to navigate to Settings -> Accessibility -> Direction lock, then toggle it on.
After toggling on Direction lock, you'll immediately be required to set your custom directional combination, which should be 4-8 directions long. Along with the combination, you'll also have to set up a PIN as a backup plan.
Once you create the Direction lock combo, look over some of the settings, which are essentially there for the blind who may need vibration or sound feedback. You can also allow directions to be read aloud or have the direction arrows visible upon performing the corresponding gesture.
With your device locked, try out your new Direction lock combination. Tip: you may not want to have the directions visible (with the "Show directions" setting) like I do in the example screenshot below.
For those who may be paranoid, thinking their fingerprint security can be exploited as they sleep, this is an option worth unlocking and trying out.