1) Maci and Bentey
Maci was in season 1 of 16 and Pregnant and later in Teen Mom, with her son Bentley, whom she had with Ryan. She has since gotten married to Taylor McKinney. We still know the Bentley you see in the picture above.
But now we are many years further and the 13-year-old (!) Bentley looks like this. He has since gotten a little brother and a little sister.