I know two. One was a high school classmate who transitioned some time after high school. Growing up he was Mike. I always knew he was different, mostly assumed he was gay. She now goes by Amy, which is how I've referred to her when we saw each other at our 30th & 40th class reunions.
The other is the youngest child of one of my nephews (the youngest child of my oldest sibling). Grew up as Fred, shortly after high school graduation began the transition to become Chloe. As with my old classmate, it was always pretty clear that he was not a straight male growing up; I wasn't overly surprised when I found out about the transition. I'm not bothered in the least, it does not impact or affect my life in any way. Some of my family, particularly one of my sisters, has had a bad time dealing with it and will not acknowledge the transition or the new name. In conversation with other family members and I, she'll refer to Chloe as "their youngest child" or sometimes still uses the male birth name. She's my sister, and I love her as a sister, but I am disgusted by her anti-gay, anti-trans, religion-driven attitudes.
