Cellar, meet Merrick:
Merrick iz speshul kat.
Merrick wakes his owner up when her blood sugar drops dangerously low, by meowing, licking and nibbling her nose, lips and ears. He's saved her life, literally, twice. Once, or twice, I'm not sure, he couldn't wake her up. So he woke up her husband.
Merrick has no training what-so-ever.