I searched the comments and surprised that no one has yet mentioned humans with XXY (Klinefelter Syndrome or KS). It is possible for them to reproduce, although usually with the help of fertility services and fertility rates are extremely low. It is possible for them to reproduce naturally as well though it's pretty rare.
FoxyTigerVixen t1_jbkciab wrote
Reply to Is there a fertile creature with an odd number of chromosomes? by TheBloxyBloxGuy
I searched the comments and surprised that no one has yet mentioned humans with XXY (Klinefelter Syndrome or KS). It is possible for them to reproduce, although usually with the help of fertility services and fertility rates are extremely low. It is possible for them to reproduce naturally as well though it's pretty rare.
A couple related articles:
https://pubmed.ncbi.nlm.nih.gov/21207006/
https://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/faqs