Mark Thomas Gilboyne (October 28, 1924 – May 5, 2010), nom de guerre Gil Boyne, was an American pioneer in modern hypnotherapy.

Contemporary influences included Dave Elman, Milton Erickson, Fritz Perls' Gestalt Therapy and Carl Rogers' "unconditional positive regard".

[4] With his background and experiences and with influences by his contemporaries mentioned above, Boyne developed one of the first programs designed to train hypnotherapists in a regression-based approach.

It uses a compassionate spiritual approach that simplifies theory in the actual therapy and hones in on allowing the inner mind to construct its own solutions creatively.

[9] From his Glendale offices near Hollywood, Gil worked with many actors throughout his career, including Sylvester Stallone, Lily Tomlin, and Dolly Parton.