Humberto Carrillo is a Mexican professional wrestler who is currently signed to WWE and is performing under the NXT and 205 Live brand. Prior to signing with WWE, Carrillo worked under the ring name of Ultimo Ninja while working in Mexico for notable promotions such as Casanova Pro, Nueva Generacion Xtrema, Lucha Libre Del Norte, Lucha Libre Azteca, The Crash Lucha Libre, and RIOT Wrestling Alliance among other notable promotions.
In 2018, Humberto Carrillo signed an official contract with WWE and started competing for the company's developmental brand of NXT. However, prior to signing a contract with WWE, Carrillo also made a few sporadic appearances for the company.
Humberto Carrillo began his professional wrestling career on December 16, 2012, when he started working for Mexican promotions under the ring name of Ultimo Ninja. During the early days of his career, Carrillo (still working under the alias of Ultimo Ninja), teamed up with El Ninja Jr. in a winning effort against Genocida and The Beast. He would then wrestle the six years for notable wrestling promotions including The Crash Lucha Libre, where the likes of Rey Mysterio, Austin Theory, and Bandido have all competed.
Other than his work in Mexico, Ultimo Ninja has also worked for promotions such as Pro Wrestling NOAH, Major League Wrestling, Baja Stars USA, and Martinez Entertainment Lucha Libre Mexicana.
On August 23, 2018, Humberto Carrillo started competing for WWE before eventually signing a contract with the company on October 18, 2018. Prior to signing with WWE, Carrillo has also made an appearance for NXT competing in a losing effort against Jaxson Ryker. Throughout the next few weeks, Carrillo would compete against the likes of The Forgotten Sons in tag team matches and would also wrestle Johnny Gargano in a losing effort.
On 15th January, 2019, Humberto Carrillo made his debut for 205 Live and in his first match on the main roster, Carrillo lost to Buddy Murphy in a WWE Cruiserweight Championsip open challenge. The following week, Carrillo secured his first win on 205 Live defeating Gran Metalik. On 27th August, Carrillo defeated Oney Lorcan to earn himself a shot at Drew Gulak's Cruiserweight Championship for Clash of Champions.