Tenchu: Stealth Assassins is a 1998 stealth video game developed by Acquire and published by Sony Music Entertainment Japan for the PlayStation. It is the first installment in the Tenchu series, with Activision releasing the game outside Japan. Following Rikimaru and Ayame of the Azuma ninja clan as they complete missions for their employer Lord Gohda in Sengoku-era Japan, the gameplay involves the player guiding their chosen character through missions, the aim being to remain undetected while either avoiding or quietly killing enemies.

Production began in 1996 as Acquire's first project, with the aim being to create a then-uncommon game using only 3D graphics, in addition to focusing on stealth over action. The team faced multiple technical challenges, and director Takuma Endo ended up taking on multiple roles within the production including scenario writer. It met with positive reception from game journalists, with praise focusing on its mission design and focus on stealth. It was also a commercial success, selling over one million units worldwide by 2003, and having estimated sales of five million across all versions by 2019. A sequel without the involvement of rights owner SMEJ, Tenchu 2: Birth of the Stealth Assassins, was released worldwide in 2000.