The disability charity the Papworth Trust has appointed McDermott as chief executive. She will join in May from the NHS Business Services Authority, where she is head of operations.
Chris Grant has been appointed chief executive of Sported, which helps disadvantaged young people to play sport. Grant is the lead facilitator on UK Sport's Elite Coach Development Programme.
Miriam Martin, director of development at Action for Blind People, has been promoted to chief executive. She has been with the charity since 1994.
The homelessness charity Porchlight has appointed Jo Pickard as director of fundraising and communications. She was head of community and events at Action on Hearing Loss.
Dominic Cotton will become interim chief executive of UK Youth, the youth skills charity, in April. He is the charity's director of communications.
The children's cancer research charity KidsCan has appointed Lowri Turner as fundraising manager.