Mermaids is a UK charity supporting transgender, non-binary and gender-diverse children and young people, along with their families. Since 1995, it has worked to help young people thrive and to make support and guidance accessible to the people around them. Its services include a support line and online chat, community groups, a youth forum, and resources for children, young people, parents and families. Mermaids also offers information for people over 18 and publishes articles and stories on topics affecting trans youth.

For professionals, the charity provides CPD-certified, trans-inclusive training for schools, organisations, health professionals, public bodies and businesses, with sessions and resources designed to foster inclusive environments. Families can find guidance on issues such as supporting a transgender child at school. Mermaids also runs a shop selling branded merchandise, with all profits supporting its work. As a charity, it relies on donations and community involvement, and invites people to fundraise, take action, volunteer or subscribe to its newsletter.