Transgender ( /trænzˈdʒɛndər/) is a general term applied to a variety of individuals, behaviors, and groups involving tendencies to vary from culturally conventional gender roles.

Transgender is the state of one's "gender identity" (self-identification as woman, man, neither or both) not matching one's "assigned sex" (identification by others as male, female or intersex based on physical/genetic sex). "Transgender" does not imply any specific form of sexual orientation; transgender people may identify as heterosexual, homosexual, bisexual, pansexual, polysexual, or asexual; some may consider conventional sexual orientation labels inadequate or inapplicable to them. The precise definition for transgender remains in flux, but includes:

A transgender individual may have characteristics that are normally associated with a particular gender, identify elsewhere on the traditional gender continuum, or exist outside of it as "other", "agender", "Genderqueer", or "third gender". Transgender people may also identify as bigender, or along several places on either the traditional transgender continuum, or the more encompassing continuums which have been developed in response to the significantly more detailed studies done in recent years.

Dr. Norman P. Spack is an American pediatric endocrinologist at Children's Hospital Boston, where he co-founded the hospital's Gender Management Service (GeMS) clinic in February 2007. He is an internationally known specialist in treatment for intersexed and transgender youth, and is one of the only doctors in the world who prescribes hormone replacement therapy to minors.

Spack has been consulted to discuss trans medical issues, often specifically pediatric in focus, in media outlets such as 20/20,Time,The Atlantic, and National Public Radio. He wrote the foreword of the 2008 book The Transgender Child: A Handbook for Families and Professionals.