Star Trek: 10 Underrated Villains
9. Commander Tomalak
The Romulans were one of the main species that vexed Captain James T. Kirk and the crew of the Enterprise on The Original Series. But by the time of The Next Generation, the powerful Romulan Star Empire had been locked away from the rest of the Alpha Quadrant for more than 50 years.
They were drawn out by the mysterious destruction of their outposts along the Neutral Zone. A Romulan Warbird encountered the Enterprise-D while it was investigating the disappearance of their own Neutral Zone outposts. While no one knew this at the time, the attacks were apparently perpetrated by the Borg as they tested the defences of their new adversaries.
Commander Tomalak became one the the more regular Romulans the Enterprise-D faced, though one of those times happened in a holodeck fantasy Riker was subjected to. That only half counts. Still, he was definitely a menacing foe who gave them a lot of trouble. The Enterprise-D only survived one encounter with him thanks to the four Klingon Birds of Prey backing them up.
As a side note, Tomalak was played by Andreas Katsulas, an actor best known to many science fiction fans as Ambassador G'Kar on Babylon 5. He was one of several actors who played roles in both universes.