Caroline Grills (née Mickelson; between 1888 and 1890 – 6 October 1960) was an Australian serial killer who poisoned her victims.

[3] She first became a murder suspect in 1947 after the deaths of four family members: her 87-year-old stepmother Christine Mickelson; relatives by marriage Angelina Thomas and John Lundberg; and sister in law Mary Anne Mickelson.

[3] Grills, a short woman who wore thick-rimmed dark glasses, commonly served her friends and in-laws tea, cakes and biscuits.

In October 1960, she was rushed to the Prince Henry Hospital at Randwick where she died from peritonitis[1] from a ruptured gastric ulcer.

In the months that followed more cases of thallium poisoning were stated, including notably, prominent Australian Rugby League footballer Bobby Lulham.