Down Darker Trails is a 2017 role-playing game supplement published by Chaosium for Call of Cthulhu.

Down Darker Trails is a sourcebook set in the American old west.

[1] John O'Neill reviewed Down Darker Trails for Black Gate, and stated that "CoC has been sorely lacking a weird western sourcebook, so I was very pleased to see Kevin Ross and his friends at Chaosium release Down Darker Trails, a massive full-color 256-page hardcover which lovingly brings Mythos horror to the old west.

The book is an excellent addition to Chaosium's catalog".

[1] Down Darker Trails won the 2018 Silver ENnie Awards for Best Monster/Adversary.