Helen

You could mean

In-universe

 * Helen, a Human nurse associated with Torchwood 3
 * Helen A, a Human dictator and leader of the Happiness Patrol
 * Helen Mortimer, a companion of the First Doctor

Real World

 * Helen Raynor, a Doctor Who story editor and writer
 * Helen Goldwyn, a voice actor for Big Finish
 * Helen Nally, an art director of Doctor Who Magazine
 * Helen Griffin, the actor of Angela Price in Rise of the Cybermen and The Age of Steel
 * Helen Worth, actor of Mary Ashe in Colony in Space
 * Helen Dorward, actor of a nurse in Spearhead from Space
 * Helen Blatch, actor of the computer in The Deadly Assasin
 * Helen Fayle, a co-editor of Perfect Timing

Other

 * St. Helen's Hospital