Killer Kross

On July 24, 2015, Kross made his Global Force Wrestling debut at the GFW Amped taping, in losing effort against Bobby Roode in the quarterfinal round of the GFW Global Championship tournament.[7] On August 21, Kross faced Joey Ryan in a losing effort during the GFW Amped taping.[8] On October 23, Kross faced Brian Myers and Kongo Kong in a three-way number one contenders match for the GFW Global Championship, which was won by Kong.[9]

Between 2015 and 2016, Kross worked multiple dark matches for Lucha Underground. On December 13, 2015, Kross made his debut for the promotion, defeating Vinny Massaro in a dark match.[10][11]

On July 11, 2018, Kross returned with a new character called The White Rabbit, he gave his wooden scepter to Paul London and ordered him to murder Mascarita Sagrada in cold blood for leading the Rabbit Tribe to his secret lair.

On March 19, 2017, Kross made his AAA debut at Rey de Reyes, helping Johnny Mundo to win the AAA Mega Championship, AAA Latin American Championship and AAA World Cruiserweight Championship. He made his in-ring debut on April 12, teaming with Johnny Mundo and Taya to defeat Argenis, Ayako Hamada and El Hijo del Fantasma in a No Disqualification six-man tag team match.[12] On June 4, Kross competed in a steel cage triple threat against El Hijo del Fantasma and El Texano Jr. at Verano de Escándalo, the match ended in a no contest after both Fantasma and Texano Jr. escaped the cage at the same time.[13] On April 20, 2018, Kross return to AAA, aligning with Juventud Guerrera and Teddy Hart to attack Dr. Wagner Jr. and Hernandez. The trio called themselves MAD.

On August 3, 2019 at Triplemanía XXVII, Kross teamed with Los Mercenarios (Texano Jr. and Taurus) to face Psycho Clown, Cody Rhodes, and the debuting Cain Velasquez, Kross' team was defeated.[14] On December 14 at Guerra de Titanes, Kross joined Rush's new La Facción Ingobernable stable.[15][16]

On the June 14, 2018 episode of Impact, Killer Kross made his debut in a backstage segment posing as a police officer, arresting Petey Williams for being the suspected mystery X attacker who had been laying out talent and personnel backstage for several weeks. Once in a secluded area backstage, however, Kross attacked and choked a handcuffed Williams, revealing himself as the actual attacker.[17][18] Kross made his in-ring debut on the July 5 episode of Impact, defeating Fallah Bahh.[19] Two weeks later, Kross defeated Williams via referee stoppage after applying a choke hold.[20]

On the August 9 episode of Impact, Kross would help Austin Aries retain his Impact World Championship against Eddie Edwards, hitting the latter with a Saito Suplex following a ref bump.[21] Aries would announce Kross as his "insurance policy" the following week.[22] The duo were joined by Moose, who betrayed Edwards during a tag team match on August 30.[23] At Bound for Glory on October 14, Kross and Moose were defeated by Edwards and Tommy Dreamer in an impromptu tag match. In the main event, Kross and Moose were in the corner of Aries as he lost the Impact World Championship to Johnny Impact.[24]

After his alliance with Aries ended, Kross entered a storyline with Johnny Impact, in which Kross tells Impact that he needed him to keep up Impact's title run much longer. At the Homecoming on January 6, 2019, Kross attacked both Impact and his wife Taya Valkyrie after the main event.[25] On the January 25 episode of Impact!, Kross challenged Impact for the World Championship, however, the match ended in a double disqualification.[26] Then at Impact Wrestling: Uncaged Kross lost a fatal four-way for the title that also featured Moose and Brian Cage.[27] Kross then entered into a feud with Eddie Edwards in May after Kross destroyed a kendo stick that was gifted to Edwards by Tommy Dreamer.[28][29] This resulted in them wrestling in hardcore matches such as a street fight and first blood match.[29][30] on the June 14 episode of Impact, Kross defeated The Sandman.

On May 13, it was reported that Kross asked for his release from Impact Wrestling following contract renegotiations. His issue stemmed from problems with his creative direction, as well as his current pay per appearance deal. He was not released at the time.[31] At Slammiversary XVII on July 7, Kross lost a first blood match to Eddie Edwards, where he reportedly refused to do a blade job and they used fake blood instead.[32] Reports indicated there was concern over "lack of blood testing and the absence of an on-site doctor."[33] Following that match he was not booked to appear at the July, August or September television tapings and the two sides continued to negotiate.[34] It was reported that his contract was set to expire in December but that the company had the option to roll it over for another year.[32] In December, Impact Wrestling released Kross from his contract.[35]

Kross made his debut for Major League Wrestling (MLW) at the Fightland event on February 1, 2020, where he defeated Tom Lawlor.[36]

Before signing with WWE, Kross made a one-off WWE appearance on the February 16, 2015 episode of Raw, where he teamed with Darren Young to face The Ascension (Konnor and Viktor) in a match that resulted in a no contest.[37]

On the February 4, 2020 episode of WWE Backstage, it was confirmed that Kross had signed with WWE.[38] In the following weeks, mysterious video packages were shown that were later to be revealed as Kross'. On the April 8 episode of NXT, Kross and Scarlett could be seen in a car watching Johnny Gargano, following his match with Tommaso Ciampa.[39] The following week, Kross debuted by attacking Ciampa.[40] On the May 6 episode of NXT, Kross, under the new ring name Karrion Kross, made his debut defeating Leon Ruff in a squash match.[41] At TakeOver: In Your House, Kross defeated Ciampa via technical submission.[42] At NXT TakeOver: XXX, he defeated Keith Lee to win the NXT Championship for the first time.[43] However, the following day on August 23, 2020, WWE announced that Kross had suffered a separated shoulder during the match, and on the August 26 episode of NXT, he vacated the title; this ended his reign at only 4 days, making it the shortest in the title's history.[44]

On the December 9 episode of NXT, Kross would return by attacking Damian Priest.[45] At NXT: New Year's Evil, he defeated Priest.[46] On the February 3, 2021 episode of NXT, Kross turned into a tweener when he attacked Legado del Fantasma (Raul Mendoza and Joaquin Wilde), before threatening their leader NXT Cruiserweight Champion Santos Escobar. Kross confronted the NXT Champion Finn Bálor after he successfully defended his title against Adam Cole on the March 10 episode of NXT.[47] He would then go on to defeat Balor at NXT TakeOver: Stand & Deliver to win the NXT Championship for the second time.[48] on the May 25 episode of NXT, Kross beat Balor again to defend the title for the first time.[49] On June 13 at NXT TakeOver: In Your House, Kross successfully retained the championship by defeating Pete Dunne, Kyle O'Reilly, Johnny Gargano, and Adam Cole in a fatal 5-way match.[50] On the July 13 episode of NXT, Gargano faced Kross for the NXT Championship with Samoa Joe as guest referee where he successfully retained. At NXT TakeOver 36, Kross lost for the first time in NXT, losing his NXT Title in the main event to Samoa Joe after a heated rivalry. This would be Kross' last match in NXT as he went to Raw.

While he was NXT Champion, Kross made his main roster debut on the July 19 episode of Raw, where he was defeated by Jeff Hardy in a non-title match, marking his first pinfall loss in WWE. This was controversial, since the NXT Champion was defeated in less than two minutes.[51] After he lost the NXT Championship, Kross was transferred to RAW and, on the August 23 episode of Raw, Kross debuted a new look where he wore a gladiator helmet and suspenders in his entrance. His new attire had negative reception from the fans.[52] WWE Hall of Famer Mick Foley talked about WWE's problems, saying that Kross' character was "greatly watered down and even made a joke of when they debut on the main roster."[53] Foley's comments were supported by another WWE Hall of Famer, Booker T.[54] On November 4, Kross, along with Scarlett, were both released from their WWE contracts.[55]