Masami Iwasaki is a Japanese voice actor born on October 25, 1971, in Tokyo, Japan. He is a graduate of Nihon University's College of Art. As of 2025, Iwasaki is affiliated with the talent management firm OgiPro THE NEXT. His career spans several decades, with active roles in the voice acting industry since at least the late 1990s. Iwasaki's physique is described as athletic, a characteristic that has been acknowledged by his peers.

Iwasaki has built a prolific career voicing a wide array of characters across anime, video games, and tokusatsu productions. He is frequently cast in roles that portray minions, ruffians, or characters with a formidable presence. One of his early and enduring roles is that of Tatsunosuke Sakonji in the long-running series Kochira Katsushika-ku Kamearikouen-mae Hashutsujo, also known as Kochikame, a part he played from 1997. Another significant and lengthy commitment has been to the Prince of tennis franchise, where he voices Wakashi Hiyoshi and Yoshiro Akazawa.

His versatility is evident in his contributions to several major franchises. In the world of Yu-Gi-Oh!, he has voiced characters across different series, including Isono in the original Yu-Gi-Oh! Duel Monsters and Principal Samejima in Yu-Gi-Oh! GX. He is also a staple in the long-running Transformers franchise, with roles such as Bighorn in Beast Wars II, Build Cyclone and Wrecker Hook in Transformers: Robots in Disguise, and Gaidōra in Transformers Go!.

More recent and prominent roles include Keisuke Itonokogiri, the bumbling but loyal detective, in the Ace Attorney anime adaptation. He voices the character in both the first and second seasons. In the remake of the classic space opera, he plays Fyodor Patrichev, the deputy chief of staff for Yang Wen-li's fleet, in Legend of the Galactic Heroes: Die Neue These and its subsequent seasons, Collision and Second. He also lends his voice to the character Norway in the popular Hetalia series, specifically in Hetalia The World Twinkle. In the world of Beyblade, he voices Lodin Haijima in Beyblade Burst GT. A more recent role is Mr. Hat in the third season of Welcome to Demon School, Iruma-kun.

Beyond these, his extensive filmography includes roles in Jewelpet: Attack Travel! as Iruka Sensei, The Asylum Session as Takayama, Planzet as Kōshirō Akejima, Yonna in the Solitary Fortress as Stan, Pokémon Generations as Shaga, and the Glitter Force Doki Doki series as both Jikochu and Proto Jikochu. He also had a role as ZZ in JoJo's Bizarre Adventure: Stardust Crusaders.

In addition to anime, Iwasaki has a notable presence in video games, particularly in the Yakuza series. He is the voice of the formidable Ryuji Goda in several installments, including Yakuza 2, Yakuza 0, Yakuza Kiwami 2, and Yakuza: Like a Dragon. He also voiced the character Raoh in the game Fist of the North Star: Lost Paradise. His work extends to tokusatsu, with guest roles in superhero shows like Seijuu Sentai Gingaman, Kamen Rider Fourze, Shuriken Sentai Ninninger, and Doubutsu Sentai Zyuohger.

Iwasaki has also participated in animated film projects. His film credits include a role in the 2019 movie Gekijōban Kochira Katsushika-ku Kamearikouen-mae Hashutsujo, reprising his role as Sakonji Tatsunosuke. He was also in the 2004 film Dead Leaves, voicing a sergeant.