For her alternate reality counterpart, see Tricia McMillan
For the film character, see Trillian's Touchstone counterpart

After all, with a degree in maths and another in astrophysics what else was there to do? It was either that or the dole queue again on Monday.
—Trillian to Arthur Dent[src]

Trillian Astra (born Tricia McMillan) is an adventurous, intelligent, and jaded human Sub-Etha radio reporter. A former astrophysicist and mathematician, she abandoned it to traverse the stars with Zaphod Beeblebrox, eventually joining the crew of the Heart of Gold and traveling the universe with them for some time.


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Compared to the other main characters, Trillian's personality and characteristics were less developed and explored. In the radio series and book, she was described as 'a rather nicely descended ape-person' and Arthur said she was 'beautiful, charming, devastatingly intelligent'. She was indeed highly intelligent, having a degree in maths and another in astrophysics, and she often offered clever and insightful suggestions throughout the story. Even though she had only been in space for a few short years, and despite only being on the stolen starship for a short amount of time, she had already figured out several aspects of the Heart of Gold, such as reading the instruments, by the time Ford and Arthur arrived on board due to the Infinite Improbability Drive, which she also had a good understanding of, despite its complex nature.

Seeing as Zaphod is 'mechanically inept' and 'could easily blow up the ship with an extravagant gesture', Ford was immediately familiar with 'only a few' of the ship's controls, and Arthur's only prior experience with spacecraft was getting ejected out of one, Trillian was easily the one with the most knowledge and expertise with regards to the Heart of Gold. The others on board the starship often turned to her for answers or information: "Trillian... is this sort of thing going to happen every time we use the Improbability Drive?." She was the person who had the most patience for Marvin and showed the most kindness towards him, despite not being sure how much longer she could stand his presence.

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"I don't think I can stand that robot much longer, Zaphod."

She was a sensible and patient individual, repeatedly finding herself as the voice of reason amongst others, especially Zaphod. One example of her ability to act rationally was when the Heart of Gold was under threat of missiles. While Ford and Arthur decided they were going to die, Trillian was taking Arthur's suggestion of using the Infinite Improbability Drive into consideration, ignoring Zaphod's wariness of the idea, and trying to ask the others if anyone actually knew a good reason why Arthur couldn't turn on the drive. Another example of her level-headed and thoughtful behaviour was when she was first introduced on the Heart of Gold when she was calmly explaining to Zaphod just how improbable it was that Ford and Arthur had been picked up by their ship.

She often acted quite nonchalant and no-nonsense, for example (in the novel), only giving Zaphod a 'tight smile' and then looking away when he singled her out in a crowd and greeted her. However, she did later smile more warmly at him, although he was looking away at the time. She was often irritated and indifferent towards Zaphod at various times, sometimes thinking him a 'terrible showoff', at other times outright ignoring him. Despite being the person who she was the least patient towards, she was also seen to reassure Zaphod and be friendly and caring towards him, so it seemed she did enjoy his company to some degree, even if he did often interrupt her focus and observations.

One of Trillian's most evident traits was her confidence and her independence. This was immediately shown with the fact that she took it upon herself to join Zaphod and travel in space instead of returning to the dole queue on Monday. She seemed aware of her intelligence and abilities and realised that exploring the universe was a good way to get as much out of life as she truly wanted. She was rarely hesitant to speak her mind - (to Zaphod) "Can we drop your ego for a moment?"- to question the men in her group - (again, to Zaphod) "You'd have been happy to let them die?" - and had no trouble getting her voice heard - "an electric pencil flew across the cabin and through the radio's on/off-sensitive airspace... she [Trillian] had thrown the pencil" (again, to get Zaphod to listen).[1] She seemed to have some of the best morals out of the group, especially compared to Zaphod and Ford's often careless nature. She also had quite a sarcastic and unapologetic sense of humour, evidenced in the novel when she says "we have normality... anything you can't cope with is, therefore, your own problem" and with her comment to Arthur from Fit the Second: "Oh, I’m sorry I missed that Wednesday lunch date, but I was in a black hole all morning."


Appearances of Trillian


  • Some drafts of the movie's screenplay, and Robbie Stamp's "making of" book covering the movie, state that Trillian was to be revealed as half-human. This would have been done in order to underline the loneliness of Arthur Dent, thus the only pure human remaining in the universe, after Earth's demolition. This idea was scrapped after the "making of" book was written, and the scene revealing Trillian's heritage (by the mice, to Arthur, on the Earth Mark II) was re-written.
  • In the original radio series, she is portrayed with a British accent — in both the TV series and movie she is played as an American. The Quintessential Phase of the radio series features Sandra Dickinson in the role of the alternate version of Tricia McMillan as a "blonder and more American" Trillian — the radio series indicates that the character is identical to the first Trillian and was born in the United Kingdom. In the book Mostly Harmless, it is said that both the alternate Tricia McMillan and Trillian have a British accent.
  • In the Hexgonal Phase of the radio series, Sandra Dickinson played Tricia McMillan and Susan Sheridan played Trillian for the section in Stavro Mueller Beta, which is how it had worked for the previous five Phases. However, due to the sad death of Susan Sheridan, Sandra Dickinson played Trillian for the rest of the first fit (episode) and Hexagonal Phase.
  • The Trillian instant messaging software was named after this character, as was the Astra instant messaging network.
  • Sigourney Weaver's character in the science fiction parody film Galaxy Quest may have been somewhat inspired by Trillian, as she laments that most of her speech is merely repeating the spaceship's computer, and how she wishes for a more substantial role.
  • Trillian comes closest of all female characters to appear in the entire "Hitchhiker's" saga.