Śakuni
Even though Śakuni’s name is associated with villainy, Śakuni is believed to be a great devotee of Śiva. It is true that Támasic characteristics were dominant in Śakuni but he too had Sāttvic elements and this was recognized by a community in Kerala, as per their folk beliefs There is an ancient temple dedicated to him at Pavithreswaram in Kollam District of Kerala.
It is believed that during the Mahābhārata battle, Śakuni traveled across the country along with his nephews, the Kauravas. When they reached the place where the temple is situated, the Kauravas set about the task of choosing their weapons and armour. From that, it got its name ‘Pakutheswaram’, which later became Pavithreswaram. The local Kuravars believe that Śakuni returned to this place after the battle and attained Mokṣa with the blessings of Lord Śiva, got enlightenment and became Lord Śakuni.
Śakuni at Pavithreswaram in Kollam District, Kerala
This temple worships a throne, which was supposedly the place where Shakuni used to sit. No Pūjā or tantric rituals are performed at the temple. Offerings to the temple include tender coconut, silk, Palm wine, etc. The temple is maintained by the Kuravar community of the region.
Duryodhana
Although Duryodhana is considered as barbaric villain commonly, but he too had some virtues. It's said that he had utmost blessings of Mātā Lakṣmī. Another of his virtues was his super-cleanliness. It's said that Śani struggled for 12 continuously to enter his body, but couldn't because of his cleanliness acc to the folklores.
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There are many places dedicated to Duryodhana’s worship.
Poruvazhy Peruviruthy Malanada Temple
It's located near the Śakuni Temple. The story behind the temple is: As part of his efforts to trace out the ‘Pāṇḍavas’ in exile, Duryodhana traversed the forests in the south and reached Malanada hill. By that time he was much tired & thirsty and went to a nearby house on the north west of Malanada and asked for drinking water. It was Kaduthamsserry Kottaram, where Malanada Appoppan, the priest and ruler of the land was staying. An elderly woman impulsively gave him toddy which she was carrying. The king(Duryodhana) enjoyed the drink, but realized after seeing the ‘Kurathali’ worn by the woman that she belonged to an untouchable lower cast by name ‘Kurava’. It was only then that the woman realises that Duryodhana is a Kṣatriyaḥ and could lose his caste by drinking toddy from an Untouchable. When she tells him this, Duryodhana says,
“Mother, there is no caste for hunger and thirst. Blessed are you for putting the interests of a thirsty man before your own safety.”
The king consoled himself and appreciated the divinity of the place and its people who possessed supernatural powers (Siddha). Thereafter, in furtherance of his ‘Rājadharma’, the king sat on the hill and worshipped Lord Śiva, praying for the welfare of his people (the prajas). As an act of charity he gave away hundreds of acres of agricultural land and paddy fields as freehold to the ‘Devasthanam’. Even now the land tax of the above property is being levied in the name of ‘Duryodhanan’.
Duryodhana Temple
There is no permanent idol as such, thus, the people have resorted to submitting themselves to their desired deity via a spiritual process called “Sankalpam”. It is widely believed that through this “Sankalpam” the devotees actually worship Duryodhana as a God.
In the Kumaon region of Uttarakhand, several beautifully carved temples are dedicated to Duryodhana and he is worshipped as the deity. The mountain tribes of Kumaon fought along with Duryodhana in the Mahabharata war; he was venerated as a capable and generous administrator.
The Jakholi Village has a temple dedicated to Duryodhana. The temple in Jakholi was built by local inhabitants Saur, who worship the Kauravas as their ancestors. Legends have it that the local people wept so much at the death of Duryodhana in the battle of Kurukshetra that their tears became a river named Tamas (meaning sorrow). There's a golden axe in the temple, which is believed to be wielded by Duryodhana.
Tamas also known as Tons, is still not used for drinking purposes as the local belief goes that the tear still continues to flow.
Duryodhana is worshipped in the upper valleys of the rivers Tons, Yamuna,Bhagirathi, Balganga and Bhilganga. This is the biggest temple dedicated to Duryodhana in Uttarakhand and other Duryodhana temples can be seen at Osla, Gangar and Datmir.
King Duryodhana came to Purola after traveling through Kullu and Kashmir. Duryodhana liked Purola so much that he decided to reside there. He prayed to Mahasu Devta for a piece of land. The deity accepted his pleas and made him the king of the area. King Duryodhana made Jakholi his capital village and constructed Mahasu Devta Temple. Duryodhana is respected and worshipped as capable and virtuos ruler here.
Jarāsandha
One of the antagonists in the Vyāsa Mahābhārata and the primary antagonists in the Jain Mahābhārata, he was the king of Magadha(modern day bihar). The present day Kahar caste people in Bihar, claim descent from him, and regard , respect, worship him as their ancestor.
Karṇa
There’s a shrine dedicated to Karṇa at the confluence of Pindar and Alaknanda, i.e. Karṇaprāyaga in Uttarakhand.
According to the popular beliefs, it is at this place Karṇa meditated to please the Sun God (his father) and was granted the impregnable armor by the deity himself.
Another legend states that, Karṇaprāyaga is the place where Kṛṣṇa buried Karṇa after his tragic death. When Arjuna fatally wounded Karṇa, Kṛṣṇa realized that the noble Karṇa is not dead as he was being protected by the Dharma- Devī due to the innumerable charitable deeds he performed all his life. It was impossible to kill Karna when the goddess was protecting him herself. Aware that victory is impossible with Dharma (righteousness) on Karṇa's side; Kṛṣṇa disguised himself as Brahmin and asked Karṇa his good merits. The wounded Karṇa on his death bed obliged and gave all his merit to the poor Brahmin. With no good merits with him anymore, the goddess of righteousness (Dharma Devī) disappeared. Kṛṣṇa nodded Arjuna to take the kill shot and before Karṇa's eyes were closed forever, the Kṛṣṇa rewarded Karṇa with the view of his Viśvarūpa. In his dying breadth, Karṇa asked the Kṛṣṇa to bury him at a virgin land which he obliged and cremated Karṇa at the holy land of Karṇaprāyaga
Rāvaṇa
These stories don't have any textual references , but are only based on folklores.