There’s been quite a few in Wisconsin. Just skimming through a handful of articles I found these people either retiring (or recently retired) or not planning to run for re-election:
Wisconsin Republican Senate Majority Leader Devin LeMahieu
Republican Assembly Speaker Robin Vos
Conservative Wisconsin Supreme Court Justice Annette Ziegler
Conservative Justice Rebecca Bradley
Republican Wisconsin State Senator Van H. Wanggaard Majority Caucus Chair
Republican Wisconsin State Senator Rob Hutton
Republican Wisconsin Senator Steve Nass