Pandyan King mentioned in Silappadikaram is Nedunjeliyan.

Explanation:
Silappadikaram is one of the five great epics of Tamil literature. It was written by Ilango Adigal during the Sangam period. The story revolves around the characters Kannagi, Kovalan, and Madhavi.

The Pandyan king who is mentioned in Silappadikaram is Nedunjeliyan. He was the ruler of Madurai during the Sangam period. He is known for his patronage of Tamil literature and art.

Some of the notable achievements of Nedunjeliyan are:

• Conquered the Chera and Chola kingdoms and expanded the Pandyan Empire.
• Built the Nedunchezhian palace in Madurai, which was known for its grandeur and beauty.
• Commissioned the Manimekalai, a Tamil epic poem, which was a sequel to Silappadikaram.
• Developed the port city of Korkai, which was an important center for trade and commerce.

Nedunjeliyan was a patron of Tamil literature and is known to have supported poets and writers. He also encouraged the translation of Sanskrit works into Tamil.

In Silappadikaram, Nedunjeliyan is mentioned in various contexts. He is mentioned as a powerful king who is feared by his enemies. He is also portrayed as a just ruler who punishes the wrongdoers and protects the weak. Overall, Nedunjeliyan is depicted as a great king who is respected by his subjects and admired by his contemporaries.