John Crichton is an astronaut and a scientist. On Earth, his scientific theories had been of such interest that IASA had allowed him to test his own theory, using the shuttle, Farscape One. However, during a test flight, John's attempt to achieve previously unrecorded speeds goes wrong when an electromagnetic wave hits, sending John, and his ship, down a wormhole.

John arrives in the uncharted territories, lost, but not alone. He is instantly surrounded by varying aliens, none more impressive than those he meets aboard Moya. He is initially brought aboard because the aliens commanding the ship aim to use his ship as an escape vessel. However, when the ship escapes Peacekeeper control, John Crichton becomes part of the crew (see Premiere).

In the uncharted territories, Crichton's adventures are many, and varied. They can however, be summarised with the following key events:

• He collides with a Prowler, killing Captain Crais's brother, causing Crais to go after Crichton with vengeance in mind (see Premiere).
• Crichton later meets the Ancients who implant wormhole knowledge inside his head (see A Human Reaction).
• When Crichton is captured by Scorpius, he has a chip implanted in his brain, leading to Scorpius having a growing degree of control over John (See The Hidden Memory and onwards).
• Crichton is later "doubled" (see Eat Me), and the two Crichtons are seperated - one aboard Moya and the other aboard Talyn.
• Unfortunately, one of the two Crichtons dies, (see Icarus Abides), but not before taking out a Scarren dreadnaught, and the wormhole knowledge it had stolen.
• The remaining Crichton then realises he must protect the knowledge he has, and will not allow the Peacekeepers, the Scarrens or anybody else to know his secret. Across Season 4, John gains a greater understanding of the knowledge, and even manages to reach Earth. However, he finds that he no longer fits in on Earth. His home is with one of the aliens he has met.