Hair Loss Curse
Description: Causes one to lose one's hair.

Hair-Thickening Charm
Description: Thickens one's hair.
Seen: In Order of the Phoenix, Snape asserts that Alicia Spinnet used it on her eyebrows even though she was obviously hexed by a member of the Slytherin Quidditch team (screw Snape and his biased ass!)

Homenum Revelio
Incantation: Homenum Revelio
Pronunciation: hom-i-nəm re-vel-ee-oh
Description: Reveals humans near the caster.
Seen: Used by Hermione upon her, Ron, and Harry's arrival at Grimmauld Place after being attacked by Death Eaters in Tottenham Court Road, after the wedding.

Homorphus Charm
Incantation: Unknown
Description: Causes an Animagus or transfigured object to assume its normal shape.
Seen: Used by Lupin and Sirius on the rat named Scabbers to reveal that he was Peter Pettigrew in Prisoner of Azkaban.

Hot-Air Charm
Description: Causes wand to emit hot air.
Seen: Used by Hermione Granger in Order of the Phoenix to dry off her robes. Also used shortly after to melt snow.

Hover Charm
Description: An object is levitated off the ground and moved according to the caster. Seen: Used by Dobby silently in Chamber of Secrets to levitate a cake, of which Harry is accused. Also used by Xenophilius to clear rubble off his stairs in Deathly Hallows.

Hurling Hex
Description: Causes brooms to vibrate violently in the air and try to buck their rider off.
Seen: In Philosopher's Stone, Quirinus Quirrell may have been casting a wordless and wandless version of this spell on Harry's broom during his Quidditch match (what?! Who knew he was that powerful?). Flitwick suggested that Harry's confiscated Firebolt might be jinxed with this spell