Tamsin is a short form of Thomasina.

• Tamsin (given name)
• Tamsin Blanchard, British fashion journalist
• Tamsin Carroll (born 1979), Australian actress
• Tamsin Cook (born 1998), Australian swimmer
• Tamsin Dunwoody (born 1958), sometimes known as Tamsin Dunwoody-Kneafsey, British politician
• Tamsin Egerton (born 1988), British actress
• Tamsin Ford (born 1966), British psychiatrist specialising in children's mental health
• Tamsin Greenway (born 1982), English netball player
• Tamsin Greig (born 1966), British actress
• Tamsin Heatley, British actress and voice artist
• Tamsin Hinchley (born 1980), Australian volleyball player
• Tamsin Mather (born 1976), British Professor of Earth Sciences
• Tamsin Pickeral (born 1971), British author and art historian
• Tamsin West (born 1974), Australian actress and singer

• Tamsin, a character in the Canadian television series Lost Girl
• Tamsin Yeobright from The Return of the Native by Thomas Hardy. Her name is given alternately as Tamsin or Thomasin throughout the book.
• Tamsin Drew, companion in the Doctor Who audio dramas.
• Tamsin, character in Return of the Indian In The Cupboard

• Tamsin (novel), a 1999 fantasy novel by Peter S. Beagle

• Tamzin
• Tasmin
• Tazmin