A clan (一族, Ichizoku; Literally meaning "family"), in the loosest sense of the term, refers to a family or group of shinobi who form a basic unit of a shinobi village. All current clans of Hikagakure immigrated into the Land of Vapor, but are treated as official clans of the village.
The Yamamoto Family is a nomadic family which originated in Sunagakure, and has been standing strong for decades. The original founder of the clan which established the name was a man named Koji Yamamoto. A man which created the legend as it is today. Now, it's becoming more notable in other regions due to the ninja known as Daichi Yamamoto who now resides in the village Hikagakure. Another notable face is his father; Mitsuo Yamamoto.
The Nii'gata Clan (竜親族一族 Nii'gata Ichizoku) is a ritualistic clan with origins that predate the world of Shinobi, and are capable of molding chakra through their mouths without needing to use hand seals. The Nii'gata are a clan unknown to nearly all normal shinobi, as they have lived and operated outside of shinobi villages for the entirety of their existence. Their name has only recently become known as Rin Nii'gata and Masakaki Nii'gata have left the clan homelands, though their abilities are left to speculation.
The Saru Clan are typically found living in forests as a preference. Since the founding of their clan they have come to see primates as their family and equals. As a result of this well developed bond from early in their childhood they grow to learn several important skills for surviving in the forest: How to forage, what plants heal wounds, which plants are poisonous? Saru clan members have a very distinct and telling traits. You'll find it to be quite obvious should you catch them with their tail released. They possess tails similar to monkeys that come out of a seal placed on their tail bone, which they have full control over. Another trait of theirs is that their canines are longer. The Saru possess a Kekkei Genkai that has been passed down through generations by the elders of the clan. At birth all members are marked with a seal above their tail bone, by the elders of the clan using Fūinjutsu, allowing them to summon a tail at will.