Kaithal (Hindi: [kɛːt̪ʰl]) is a city and municipal council in the Kaithal district of the Indian state of Haryana. Kaithal was previously a part of Karnal district and later, Kurukshetra district until 1 November 1989, when it became the headquarters of Kaithal. It shares a border with the Patiala district of state Punjab and the Kurukshetra, Jind and Karnal districts of Haryana. Kaithal district is situated in the North-West of the Haryana state. Its North-West boundaries, which include Guhla-Cheeka are attached to Punjab.

Historically the city was known as Kapisthal, meaning "Abode of Kapi", another name of Lord Hanuman, and it is said to have been founded by the Pandava Emperor, Yudhishthira of Mahabharata. The later word Kaithal is said to be derived from Kapisthala. It is traditionally connected with Hanuman and has a temple dedicated to Anjani, the mother of Hanuman. It is also said that it is the birthplace of Lord Hanuman and there is a temple constructed at that place known as "Anjani Tila" among the residents of Kaithal.

The Vridhakedara (Vidkyar) sanctum of Kaithal finds a mention in the Vamana Purana. Kaithal, with many of its temples, is also an important milestone in the 48 Kos Parikrama pilgrimage.

Timur stopped here in 1398, before attacking Delhi. Later, the city became a Muslim cultural centre, under the rule of Delhi Sultanate. Tombs of several Sufi saints dating from the 13th century can be found in the city today; most important among them is that of Sheikh Salah-ud-din of Bhalkh (Balkh?) (1246 CE). The town was renovated and a fort was built during the rule of the Mughal Emperor, Akbar, and as per Ain-i-Akbari, it was a pargana, under the sarkar of Sirhind, and had developed into an agricultural centre.

Razia Sultan, the first Muslim woman ruler of Delhi, reigned as the Sultan of Delhi Sultanate from 1236 to 1240. She fled Delhi with Malik Altunia after they were defeated on the 24th of Rabí'u-l awwal A.H. 638 (Oct. 1240), and reached Kaithal the next day, where their remaining forces abandoned them, and were killed on 13 November 1240. The tomb of Rajia Begam is still found here. This aspect is still not well known outside Kaithal, but residents know about the Mazaar of Razia Begum even generations later.

Timur took the town in 1398, with his army massacring or plundering the inhabitants and destroying all villages along the way to Assandh. Many of the residents of Kaithal and the other cities had fled to Delhi in fear.

In 1767, the city fell into the hands of the Singh Krora Misl chieftain, Bhai Desu Singh (d. 1781), who led a large Sikh force from his native village of Bhucho, establishing the Kaithal State. In the Punjab whose descendants, the bhais of Kaithal, ranked among the most powerful Cis-Sutlej states. The Sikh Chieftains of Kaithal, ruled from 1767 until its fall in 1843. By 1808, it came under British influence. The state was ruled by the Scindhia dynasty of the Maratha Empire and paid tributes to the Marathas, until the Second Anglo-Maratha War of 1803–1805, after which the Marathas lost this territory to the British. Bhai Udey Singh ruled over Kaithal and proved to be the last King. Bhai Udey Singh died on 14 March 1843 and State become part of Thanesar District & transfer to Punjab province in 1849 along with Cis-Sutlej states. which later abolished in 1862 and kaithal area become part of karnal district tahsil. Kaithal town became a municipality in 1867. In 1901, the town had a population of 14,408. The fort of the Bhais is still extant, and their title Bhai became common with the primary Jat Sikh rulers. Peoples of Kaithal took active part in the freedom struggle in 1857.

Kaithal is located at 29°48′05″N 76°23′59″E / 29.8015°N 76.3996°E / 29.8015; 76.3996. It has an average elevation of 220 metres (721 feet).