Helena Kathleen Isdell (30 November 1888 – 23 October 1915) was a New Zealand nurse who served in the First World War and died in the sinking of SS Marquette in 1915.

She left Wellington in July on the SS Maheno, travelling with 69 other New Zealand nurses, and arrived in Port Said, Egypt, in August.

[2] On 19 October, the hospital unit boarded the SS Marquette in Alexandria, but four days later it was sunk by a torpedo from a German submarine.

Isdell's body was found in a lifeboat, along with that of Margaret Rogers and four men, which washed up on the shore near the Greek town of Zagorá.

[3] Isdell is named on the Mikra British Cemetery in Greece and in the Nurses' Memorial Chapel at Christchurch Hospital.