Cool! I meant where do they appear other than in LEGO form.
The shadow stormtroopers acted as the personal stormtrooper unit of the head of Imperial Intelligence, Agent Blackhole, which earned them their moniker of "blackhole stormtroopers." They frequently underwent special training in infiltration and ambush tactics, and were often assigned to extremely classified missions.
I haven't heard of Agent Blackhole. But is there Shadow Stormtroopers as well as Shadow troopers?