Clea is the Sorcerer Supreme and occasional ruler of the Dark Dimension. She is the daughter of Umar and niece of Dormammu, the Faltine warlords who took over the Dark Dimension after the death of Olnar, the last of the Mhuruuk wizard kings who had previously ruled the Dark Dimension for thousands of years. Umar had an affair with Olnar's son Orini, resulting in Umar becoming pregnant and giving birth to Clea. Umar abandoned Clea into Orini's care and he raised her in complete ignorance of her relationship to Umar and Dormammu. Clea became Stephen Strange's ally in the Dark Dimension, resulting in her nearly being killed by Umar and imprisoned by Dormammu. To save her, the Ancient One hid her in a pocket dimension, where Stephen Strange eventually found her and brought her to earth. She became Strange's lover and his magical disciple. Strange taught her all the magic he knew. Although Clea and Strange loved each other deeply, she eventually returned to the Dark Dimension to liberate it from Umar and Dormammu. She led a rebel army and eventually defeated Umar - who Clea learned was her mother - and then she became the new ruler of the Dark Dimension. Clea and Strange were married in a Dark Dimension ceremony and the pair agreed that each would stay in their own home dimension to protect it, but they would still get together whenever they could. Eventually the two became estranged and separated, though Strange was not willing to officially end the relationship. Dormammu took over the Dark Dimension again and Clea fled to Asgard for a time. Clea and Strange got back together during a fight with Galactus. To win that battle, Strange made a deal with Mephisto that meant sacrificing the one thing that meant the most to him: Clea. Strange wiped all of her memories of him and left her in the Dark Dimension. Her memories were restored after Strange's death in the Death of Doctor Strange mini-series. As a result of the events in that series, Clea has become the Sorcerer Supreme of the Earth Dimension. She has vowed to retrieve his lost soul and bring him back to life. This is the basis for the new series, Strange which debuts in March 2022.

Clea first appeared in Strange Tales #126, back in 1964. In all those years, she's largely been a supporting character in the various Doctor Strange series or in the Defenders, and only rarely appeared in other titles. The new Strange series by writer Jed MacKay is the first time that she is being featured as a leading character in her own right, so it seems like a good time to establish an Appreciation thread for her and this new series. Clea has not yet made an appearance in any of the MCU films. It's unknown at this time if she will be appearing in the next Doctor Strange film. She has appeared as an NPC and a playable character in some of the Marvel games.