Guinan is a fictional character in the Star Trek universe. She first appeared in the second season of Star Trek: The Next Generation. Due to a long friendship with Captain Picard, she was invited to serve as the host of the Ten-Forward lounge, a bar aboard the Enterprise-D where her wise counsel proved to be a valuable asset.

Guinan is an El-Aurian from El-Auria. Her people, sometimes called "listeners," were scattered through the galaxy when the Borg invaded their homeworld. As a refugee aboard the El-Aurian vessel Lakul, she was rescued from the Nexus by the Enterprise-B. Later, she is present for the wedding of William Riker and Deanna Troi.

Her species is long-lived (the TNG episode "Time's Arrow" reveals she lived on Earth in the late 19th Century), and they apparently have some powers beyond what is associated with humanoids. Q seemed to treat her as an equal in his encounters with her. In the episode "Yesterday's Enterprise," she was able to sense that the reality they ended up in was not the proper flow of time, even though everyone else believed it to be the natural course of events.

The character was named for famed saloonkeeper Texas Guinan.

Guinan was played by Whoopi Goldberg. According to her, she approached the creators of Star Trek with her desire to be on the show. At first the creators did not think they could create a role suitable for such a highly rated actress, until Whoopi Goldberg revealed that she didn't care how big or small the role was, even if all she did was sweep the floors. It was from this the creators decided to give her the role of a barmaid