Hij'qa was a Klingon warrior on the ship traveling to Gre'thor (or Klingon Hell) where dishonored souls are taken.

He approached B'Elanna Torres and held a branding iron to her cheek. However, it didn't brand the Klingon emblem upon her since she was not yet meant to die. (VOY: "Barge of the Dead")

This Klingon was portrayed by Sherman Augustus.
According to the script, he was described as one of "four undead Klingon warriors [...] his eyes black and soulless."
The authors of the Star Trek Encyclopedia (4th ed., vol. 1, p. 336) thought Hij'Qa "may (or may not) have been a hallucination."