In Jainism, there are 24 Tirthankaras (the Chouvisi Bhagwan) in every time cycle. The current cycle ends with Mahavira, who is the 24th Tirthankara, so there is no “next” Tirthankar in this cycle. The names of the 24 Tirthankaras in the present cycle are generally listed as: Rishabhanatha, Ajitnatha, Sambhavanatha, Abhinandananatha, Sumatinatha, Padmaprabha, Suparshvanatha, Chandraprabha, Pushpadanta (Suvidhinatha), Shitalanath, Shreyansanath, Vasupujya, Vimalanath, Anantanath, Dharmanath, Shantinath, Kunthunath, Aranath, Mallinath, Munisuvratnath, Naminath, Neminath, Parshvanath, Mahavira.

• If you want, you can read more about the “next cycle” Tirthankaras (the 24 Tirthankaras of the coming utsarpinī) here .
• For a concise note on Mahavira as the 24th Tirthankara of the present cycle, you can also refer to this page .

If you meant something different by “next” or want the Arth (meanings) of a specific Tirthankara, tell me which one and I’ll explain in simple Jain terms.