We've seen TV characters get hypnotized in the past, usually for comedic purposes. My personal favorite is when Rob Petrie was hypnotized to act drunk whenever a bell rang on 'The Dick Van Dyke Show'.
Here's what my old TWD standby Wikipedia has to begin their article on hypnotherapy:
Hypnotherapy is therapy that is undertaken with a subject in hypnosis.
The word "hypnosis" (from the Greek hypnos, "sleep") is an abbreviation of James Braid's (1843) term "neuro-hypnotism", meaning "sleep of the nervous system".
A person who is hypnotized displays certain unusual characteristics and propensities, compared with a non-hypnotized subject, most notably hyper-suggestibility, which some authorities have considered a sine qua non of hypnosis.
For example, Clark L. Hull, probably the first major empirical researcher in the field, wrote,
If a subject after submitting to the hypnotic procedure shows no genuine increase in susceptibility to any suggestions whatever, there seems no point in calling him hypnotised [...]
(C.L. Hull, Hypnosis & Suggestion, 1933: 392)
Hypnotherapy is often applied in order to modify a subject's behavior, emotional content, and attitudes, as well as a wide range of conditions including dysfunctional habits, anxiety, stress-related illness, pain management, and personal development.