One of the many ways in which you can customize your Guardian is by equipping a Title. A Title will place a little snippet of purple text beneath your Gamertag for other players to see. Each new season of Destiny 2 gets its own correlating Title, and to unlock it, you have to complete some Triumphs. Here is how to get the Reaper Title by completing all of the Season of the Haunted Triumphs in Destiny 2.
All Season of the Haunted Triumphs for the Reaper Title in Destiny 2
There are a total of 10 Triumphs that Guardians will need to complete in order to unlock the Reaper Title. Here are all of the Triumphs and their requirements:
Related:How to get the Iron Lord title in Destiny 2

Collecting all of these Triumphs will net you a few Exotic items along the way and reward you with the Reaper Title.
For more Destiny guides, check outChanges coming to Solar 3.0 in Destiny 2right here on Pro Game Guides.