3. Clea
Clea is probably the most likely character on this list to make a future appearance in the MCU, thanks to her strong association with Doctor Strange (who is due to appear in Phase 3), but nobody has really given her a passing thought. That's something of a shame, because she's a fantastic character. Thanks to being the daughter of Umar, Clea is the niece of Dormammu - Doctor Strange's greatest and most powerful foe - and is subsequently a very powerful sorceress. When she was watching Strange battling Dormammu from her own dimension (which she ruled), she was so impressed by his courage against her Uncle that she stepped in to help. After helping each other several times again following this incident, Clea would come to live with Doctor Strange. However, she struggled to adapt to Earth and was worried about the fact that her powers were diminishing - something which was rectified by a trip to Stonehenge. Later the two exchanged vows and became married and would go on to battle the likes of Thanos together - something they could help the Avengers with in the MCU. Essentially, a female with magical powers would be a great addition to the MCU and some of the stories that Clea could be a part of - if the comics are any indication - are fantastic.