Turlough is an alien from the planet Trion who seeks to kill the Fifth Doctor on orders from the antagonist known as the Black Guardian.

Strickson was requested to be cast in the part by his agent, and was one of the last actors producer John Nathan-Turner saw in the auditions for Turlough's character.

Other critics felt the character's writing quality varied, though he has received analysis in the book Who is Who?, which analyzed his development as a result of his interactions with the Doctor.

Turlough makes a brief cameo in the following serial, The Caves of Androzani, where he appears as a hallucination encouraging the Doctor not to die.

It was deemed boring for the character to hold strictly to the concept of "evil companion turned good", and thus it was decided that Turlough would continue to show hints of potential betrayal even after proving himself to the Doctor.

[1] Lead actor Peter Davison remarked that it was one of producer John Nathan-Turner's attempts to give the Doctor a "companion with attitude", citing previous examples like Adric and Tegan.

[1] With a cast celebration party imminent on Angels, Strickson went to the home of Nathan-Turner and held his audition for Turlough there.

[3] During filming, Strickson had gripes with the "two-dimensional" acting of the show, and attempted to give Turlough more depth by building relationships in the background.

He disliked the filming of the episode Terminus due to its atmosphere and because the amount of crawling Strickson had to do resulted in his costume's trousers becoming worn out.

He stopped after an incident filming Enlightenment, in which a harness attached around the actor's crotch broke, causing injury.

According to Strickson, there are many outtakes where he had to stop filming because the prop's light was too hot and threatened to burn his hand.

[3] Turlough's role was very political, and his exile and backstory in relation to his home planet Trion acted as an allegory for what was going on in Poland during the period of the Iron Curtain.

Muir, despite his criticism, praised Strickson's performance, and found Turlough's ending in Planet of Fire to be "satisfactory".

They felt that his reunion with his species in Planet of Fire made the character appear gullible, unlike his prior characterization.

[7] Tanya Huff, writing in the book Queers Dig Time Lords, described Turlough's tendency to keep secrets, as well as the character's intensity, to appear akin to a romantic partner for the Fifth Doctor, which Huff cited as laying the ground for the eventual debut of Jack Harkness, the show's first openly bisexual character.