Tulak was a hologram, based on Tuvok, in The Doctor's holonovel entitled Photons Be Free. In the novel, Tulak was a Human who served aboard the USS Vortex. Unlike Tuvok, Tulak wore a goatee and had shades of grey in his hair.
In "Chapter 7: The Escape", he and Ensign Kymble took the EMH character into custody on orders from Captain Jenkins, with the intention to reprogram its holomatrix. He was stopped by Three of Eight, a character based on Seven of Nine who rescued the EMH. However, the EMH was soon recaptured and reinitialised in "Chapter 8: A Tragic End". (VOY: "Author, Author")
Like Tuvok, Tulak was portrayed by Tim Russ.
From the Star Trek Encyclopedia (4th ed., vol. 2, p. 427), "Photons Be Free was presumably published some time after the conclusion of the episode, albeit in revised form. We suspect that the final version of the character was less like Tuvok, and may even have had a different name."