S05E18 where Quark becomes an arms dealer when he's struggling for money. His cousin Galen sets him up as a salesman, and the other guy in the picture is Galen's boss
Are you maybe thinking of the also fabulous Wayne Pygram (Scorpius), or Shane Briant (Kaarvok)? Cause Steven Berkoff (Hagath), even though he would've fit right in, wasn't on FS, unfortunately... Unless there's a joke or another reference which I'm missing, which is also 100% possible, lol
Durka! I thought about his character, too, but I couldn't remember the actor's darn name, or character name, only that he also fucked up Moya and her crew, lol. I can absolutely see their resemblance, most definitely. So many menacing pale dudes in great sci-fi shows