Aich (surname)
Aich (also spelled as Aitch) is a Hindu Bengali surname belonging to the Maulika Kayastha caste.

Kayasthas are a sub-caste of Hindus, found across both historical and modern India. The Kayasthas emerged as a sub-caste or Caste of the Kshatriyas in Bengal during the 5th–11th centuries AD. Unlike Chitragupta Kayastha families in Northern India, Bengali Kayasthas claim their origin from King Bhadrasen and his subjects. Some of them even formed their own independent Kingdoms for example the Deva dynasty, Chandra dynasty, Shur dynasty etc. In medieval Bengal, Kayasthas were able to play a key role under Muslim rule by learning foreign languages such as Persian.

After the defeat of the Afghan rulers of Bengal by the Mughals at the battle of Patna in 1576, some Bengali warlords or zamindars played a key role in resisting further Mughal advancement into Bengal for some time. Famous among them are the "Baaro Bhuiyan" (lit. twelve "bhuiyan" or landowners), partially independent zamindars, who fought for around 50 years resisting Mughal rule.

Prominent of the "Baaro Bhuiyan"s who were Kayasthas included: Chand Ray, Kedar Ray, Mukunda Ray, Maharaja Pratapaditya of Jessore, Kandarpanarayan (whose son Ramchandra married Bindumati, the daughter of Pratapaditya) of Chandradveep (modern Bakherganj) etc.

The Kayastha Aitch (Aich) trace their ancestry to the Aditya clan of the Kayasthas of modern-day Bangladesh – the clan that Pratapaditya (and his son udayaditya) of the Baaro Bhuiyans belonged to. It is believed that the original name of Aditya, over time, changed to Aithya to Aith to Aitch (Aich) in the local dialect of East Bengal (now Bangladesh).

Brahmin Aitch (Aich) 

Aitch (or Aich) are also found among the Baarendra Brahmin sub-caste of Bengali Brahmins.

Oriya Aich or Aech 
Aich or Aech are also found among the Oriya Khandayat.

Kayastha
Social groups of West Bengal