Dejan Tumbas (Serbian Cyrillic: Дејан Тумбас; born 5 August 1999) is a Serbian professional footballer who plays as a Forward or a Left back for Indonesian club Persebaya Surabaya.

Born in Krivaja, FR Yugoslavia, Tumbas started off youth career in Hajduk 1912, a small club in Serbia with a long history. Then, he joined Partizan U19 in 2016. He started his senior career with joined numerous clubs in the Serbian First League and Serbian SuperLiga between 2017 until 2023.

In 2023, Tumbas signed a contract with Montenegro team Rudar Pljevlja. He made his league debut for the club on 18 February 2023 as a substituted in a 0–1 lose against Mornar Bar. On 9 March 2023, he scored his first league goal for Rudar in a 2–3 away win against Petrovac. On 15 April 2023, he scored a brace for the club in a 3–1 home win against Iskra Danilovgrad. Tumbas added his fourth goals of the season on 7 May 2023 with one goal against Petrovac in a 4–2 home win.

In August 2023, Tumbas decided to Tajikistan and sign a contract with Khujand. He made his club debut in a 1–1 draw against on 13 August 2023 as a substituted.

On 16 September 2023, Sloboda Užice announced the signing of Tumbas. Tumbas made his club debut in a 0–0 draw over Mačva Šabac on 22 September 2023 as a starter.

On 18 July 2024, Tumbas left Sloboda Užice after eighth months, and he decided return to Khujand.