Tsugumi Ohba (Japanese: 大場 つぐみ) is the pen name of a Japanese manga writer, best known for authoring the Death Note manga series with illustrator Takeshi Obata from 2003 to 2006, which has 30 million collected volumes in circulation. The duo's second series, Bakuman. (2008–2012), was also successful with 15 million in circulation. In 2014, Ohba collaborated with My Little Monster creator Robico for the one-shot "Skip! Yamada-kun". Another series with Obata, Platinum End, was serialized in the monthly Jump SQ from November 4, 2015, to January 4, 2021.

There is speculation that Tsugumi Ohba is a pen name and that the real identity behind it is a closely guarded secret. Some believe the pen name belongs to Hiroshi Gamou, known for the manga series Tottemo! Luckyman, which was adapted into an anime in the 1990s. Another theory identifies the pen name with Yuko Asami, a Shonen Jump artist responsible for titles such as "Wild Half", "Romancers", and "Jump Run". It is presumed that "Death Note" may be Asami's first written work, which is why the pen name Tsugumi Ohba was used.

Interestingly, the character "L" from the Death Note series is thought to be based on Ohba's own personality, especially due to the use of an alias and not being seen in public. Traits such as a love for snacks, thinking day and night about things, and sitting in an unusual manner are seen in both Ohba and the character "L".

Ohba is born in Tokyo and has a hobby of collecting tea cups. Day and night, Ohba develops manga plots while holding his knees on a chair, a habit reminiscent of the character "L" from Death Note.