Are you perhaps thinking of:
* Mikaela Banes: The female lead in the first two Transformers movies (2007 and 2009), played by Megan Fox.
* "Megan" in the Transformers: Animated series: This character is a minor character in the show, a teenage girl who helps Bumblebee and Prowl.
* "Megan" from the Transformers: Rescue Bots series: This character is a young girl who is best friends with the Rescue Bots and helps them save the day.
Please clarify the context or specify which Transformers media you are referring to, and I can help you further.