10 Worst Injuries Star Trek Characters Actually Survived
3. Riker Loses An Arm
In Schisms, the Enterprise-D is visited by a race of aliens who seem to be the very template for alien abduction in literature. They visit various crewmembers at night, dragging them into their own universe, and conducting horrible experiments on people - sometimes leading to their deaths. The unfortunate Ensign Hegler found out the hard way that serving aboard a starship is never risk free.
However, it is Commander Riker who survives, though not without cost. As he visits sickbay for an explanation as to why he feels as rough as he does, Dr. Crusher discovers to her amazement that Riker's arm has been severed - and reattached. This all happened during the night, with Riker never being aware of the procedure.
Never mind the psychological trauma of discovering someone had been hacking at him while he slept, but Riker was far from free of these beings. They continue to visit the crew of the Enterprise, only stopping once Riker turned the tables on them. He manages to escape, along with Ensign Ragar, but not before the aliens send a homing beacon through the portal. It may not be the last time that Riker meets them.