Suzie Johnson, also known as Doctor Mother or Suzie Cakes-Johnson, is Baby Cakes' mother as well as a scientist who studies testosterone. In addition, she is Leonard's ex-wife and now Dwayne Johnson's wife.
Doctor Mother is first mentioned in "Dream Reamer" by Baby Cakes, who asks his father, "Did you find Mom on Facebook and bury a hatchet in her?"
As shown in "Parent's Day", Doctor Mother does various experiments; one experiment caused Steve Urkel and subsequently the Dean to grow to enormous size and destroy lots of property. Following a brief reunion with Leonard to combat the giants, the two make it clear to Baby Cakes that they will not be reuniting, though they do still respect each other.