Tricia Marie McMillan, usually known as Trillian and sometimes Trillian Astra, is a human astrophysicist and mathematician whom Arthur Dent completely failed to chat up at a party at a flat in Islington.

Trillian eventually left the party with Zaphod Beeblebrox, who was directly responsible for her nickname.[1] The next time she and Arthur met was on a spaceship in deep space, six months after their first encounter and shortly after the Earth had been destroyed by the Vogons to make way for a hyperspace bypass.

Sandra Dickinson as Trillian

Trillian on the Heart of Gold

She is carried off and forcibly married to the President of the Algolian Chapter of the Galactic Rotary Club,[1] though this actually occurred in the artificial universe within the Guide offices. Trillian then saves the universe from the Krikketers, and later becomes a Sub-Etha Radio reporter under the name Trillian Astra.


Trillian comes closest of all female characters to appearing in the entire "Hitchhiker's" saga.


Featuring Susan Sheridan (later Lynne Moore) as Trillian

Primary PhaseEdit


Featuring Cindy Oswin as Trillian



Featuring Sandra Dickinson as Trillian

Computer gameEdit


Featuring Zooey Deschanel as Trillian

Behind the scenes Edit

  • Trillian was played on radio by Susan Sheridan.
  • She was portrayed on television by Sandra Dickinson, who also reprised an alternate-universe version of the role in the fifth and final radio series
  • Cindy Oswin played the role of Trillion??
  • She was portrayed on the 2005 film by Zooey Deschanel.

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 100% Homo Sapiens 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.

The Trillian instant messaging software was named after this character, as was the Astra instant messaging network.

Notes and referencesEdit

  1. 1.0 1.1 According to the Quintessential Phase