Koodiyattam (Koothiyattam or Kutiyattam) is derived from the Sanskrit word Kurd, meaning to "to play", and is considered to have been introduced in India by the Aryans. Koodiyattam is the oldest existing classical theatre form in the entire world, having originated much before Kathakali and most other theatrical forms. It is considered to be at least 2000 years old.  This theatre form originated in Kerala but the exact date of its inception is not known. It is widely believed that Kulasekhara Varma Cheraman Perumal, an ancient King of Kerala, was the creator of Koodiyattam in the present form. His book 'Aattaprakaram' is considered as the most authoritative work on the art form till date. The 10th century chronicles of the Varman dynasty record the art form in its advanced stages, pointing to its much earlier origin.  The dance also finds a mention in Ilangovan's 1500-year old Tamil Classic Chilappathikaram as 'Kerala Chakkian Sivanadanam'.

Koodiyattam is the most prominent survivor among the forms containing some essential elements of content and structural features of the Sanskrit theatre. Experts consider Koodiyattam to be more advanced than Kathakali, the better-known classical art form of Kerala, in aesthetics and theatre practices. But it never captured the public imagination even in its home state and was limited to a few koothambalams or temple theatres. Koodiyattam has survived over the years because practising families have maintained the tradition in an orthodox manner. At the same time, they have adapted the art form to suit a wider audience by using local dialects and secular texts. Koottu (Chakiar Koottu) is considered as the precursor of Koodiyattam.

 
Traditionally, Koodiyattam is presented by Chakyars, a temple caste of Kerala, and Nangiars, the women of Nambiar caste. Koodiyattam, unlike the most other theatre forms allows an active role for women. The Nangiars recite shlokas and play female characters. Recently, a Nangiar called Margi Sathi created history by penning an attaprakaram (guide for actors) for the play Sriramacharitham.

Koodiyattam was traditionally a part of the temple rituals, performed as a kind of visual sacrifice to the deity and is normally performed in koothambalams or temple theatres that are decorated with exquisite carvings. Conventional in its make-up, costume as well as form, it is an elaborate blend of symbolic gestures, stylised movements and chanted dialogue and verse in Sanskrit, Prakrit and Malayalam. Sanskrit plays of the 7th or 8th century AD like Bhasa's Abhishekanatakam, Mahendra Vikraman Pallavan's Mathavilasam and Kulasekhara Varma's Subhadra Dhananjayan are among the most commonly enacted Sanskrit plays in Koodiyattam. Plays of the 11th century AD like Kulasekhara Varma's Subhadra Dhananjayam and Sakthi Bhadra's Ascharyachoodamani are also staged. The musical instruments Mizhavu and Edakka provide the background music to Koodiyattam. Through sound modulation, the percussion instruments augment the effect of acting in this dance drama.

In Koodiyattam, there is a Vidooshaka (Royal clown) who humourously narrates the thematic development of the text, to the audience in Malayalam. His words and actions convincingly portray the true character of the protagonist.  In  the past he was a social auditor.  His diatribes against the establishment and those in power were a corrective force in the feudal-society. 

All the main characters in Koodiyattam customarily enact Nirvahana, a recollection of past events in the story, to form a background for stepping into the present. This is always a long drawn out affair and might take anywhere from a few days to a number of weeks. It takes 20 days to enact an act of a Koodiyattam play, with 5 hours of performance a day.  Each act is divided into Poorvangam (preamble), Nirvahanam (solo performances) and Koodiyattam (group acting). Each segment lasts four or five days. The acting can be so elaborate that the Chakyar or Nangiar, the actress, may need a day to interpret just one phrase.

The four-fold concept of acting dealt with in the Natya Shastra find its due significance in Koodiyattam.  Angika (hand-gestures and body-movements), Vachika (verbal acting), Aharya (make-up and costuming) and Satwika (facial expressions) in Koodiyattam are highly stylised.  One finds in Koodiyattam more of Natyadharmi (stylised Acting) compared to other classical art forms.  

Ammannur Madhava Chakyar (May 13, 1917-July 1, 2008) is considered as one of the greatest exponents of Koodiyattam. D.Appukuttan Nair promoted this art form in the middle of the last century by constructing two koothambalams at Adyar (Chennai) and Kalamandalam (Kerala).  He also started a Koodiyattam course at Kalamandalam. There are four reputed centres of Koodiyattam: Margi, Kalamandalam, Ammannoor's Chachu Chakiar Smaraka Gurukulam and Lakidi (founded by P.K.Narayanan Nambiar, mizhavu expert).

In May 2001, Koodiyattam earned a rare honour when UNESCO declared it a masterpiece of human heritage to be protected and preserved.  There were 31 other 'contestants' from the world over, including Japan's Nogaku theatre, China's Kunqu opera and Spain's Elche play, but it was Kerala's theatre art that UNESCO selected as the endangered heritage art form worthy of its support. The UNESCO jury in Paris decided to honour Koodiyattam after watching 15 minutes of a 3-hour documentary film made by the veteran film-maker Adoor Gopalakrishnan on the request of Margi, a Thiruvananthapuram-based dance school.  In its citation the UNESCO mentioned that Koodiyattam represents a vital link to ancient heritage and "is an outstanding example of tradition-based creation of a cultural community".  This was the first time that the UN body had conferred the heritage status on an art form.