Billy Kapowski

"Zack!"

- Billys first words

Season 1
Billy Kapowski is Kelly's baby brother, whom she placed in the care of her friends, so that she could have her cheerleading picture taken for the school yearbook. Zack was often left alone with Billy as the others made excuses or had other commitments to attend to. Because of this, Billy and Zack bonded quickly to the point where Zack distrusted anyone but himself to care for the baby. He was forced however to allow Jessie and Lisa to look after him in their Home Economics/Parenthood class. They lost track of Billy when Screech went to fetch Billy for Zack but mistook a doll for the baby. The gang eventually found him in Mr. Belding's office and at the end of the episode he spoke his first word: “Zack.”