STH can refer to:
- STH (gene), a human gene
- Somatotropin hormone, now more commonly referred to as growth hormone
- Subtropical High, a band of atmospheric high pressure found between 30 and 35 degrees both north and south
- St Thomas' Hospital in London
- St. Helen's School, an independent girls school in a suburb of London
- Sheffield Teaching Hospitals NHS Foundation Trust
- Something, an existential quantification
- Sonic the Hedgehog (character)
- "Stairway to Heaven", a song by the rock band Led Zeppelin
- Shrek the Halls, a TV special
- Stockholm, capital of Sweden
- Shadow the Hedgehog (character)