The overall Alienizers are the main antagonists of Tokusou Sentai Dekaranger.
Most of Alienizers are independent criminals. While some Alienizers might work together towards a common goal, or be part of a particular criminal organization or family, the majority of Alienizers have been known to work independently from each other. However, the majority of them have purchased weapons and Mechanoids from an arms dealer Alienizer, called Agent Abrella, making Abrella ultimately responsible for their vile actions in the series.
As a result of this, even after Abrella's demise at the finale of the series, there are still Alienizers wreaking havoc in their criminal activities, which comfirmed Abrella's final words that the crime will never disappear.
In Kaizoku Sentai Gokaiger, Buramudo, an Alienizer, took a job for the Zangyack Empire to oversee their plot to launch subterranean missiles to destroy every city on Earth. After his plan is thwarted and he is defeated by the Gokaigers assuming the forms of the Dekarangers, an enlarged Buramudo is destroyed by Deka Gokaioh.
- Agent Abrella (weapons dealer)
- The Three Hell Siblings - charged with mass murders, destruction of 79 planets, creating chaos on Earth.
- Algolian Gas Drinkers
- Amoreian Baachiyo
- Lovelian Balance - charged with hostage taking.
- Diamantian Don Moyaida - charged with murder of police officer, hit-and-run, robbery of planetary resources.
- Grorserian Hell Heaven - charged with kidnapping, murders from 29 planets.
- Rikomoian Kevakia - charged with kidnapping.
- Anrian Beildon - murders and gasolinization of humans from 5 planets.
- Doltockian Manomerk - Being part of Beildon's plan.
- Juuzaiann Braidy - Actually not an alienizer, just attacked cars in a Vengeful rampage after the death of his family. charged with obstruction of justice and vandalism.
- Ridomihan Kersus - charged with mass murders and multiple planetary invasions.
- Quotaian Dagonel - charged with turning humans into figurines from 24 planets.
- Zamuzan Sheik - charged with 82 planetary and satellite destruction, crimes against universal peace.
- Intergalactic Hitman Gigante - charged with assassinations.
- Kajimerian Ben G - charged with blackmailing, kidnapping, contract killing from 13 planets, illegal land speculation.
- Cristonian Ferley - charged with 257 accounts of robbery-murders from 19 planets.
- Titanian Meteus - charged with illicit weapon manufacturing, vandalism, murders from 34 planets.
- Ozchuian Ial - charged with narcotics code violation, turning humans into dumplings from 35 planets.
- Wojonian Jinche - charged with hijacking Dekabase, impersonation of police officer, 58 accounts of murders from 7 planets.
- Guermerlian Byz Goa - charged with 15 planetary destruction, attempted destruction of Earth, disturbance.
- Dradian Goldom - charged with kidnapping, incitement, bank robberies and murders from 99 planets.
- Spiritian Byoi - charged with crimes against people through their body possession from 48 planets.
- Bandarean Jeeva
- Beesian Beeling - charged with causing disturbance.
- Barigean Milibar - charged with thefts and murders from 48 planets.
- Pouchien Bolapen - charged with multiple accounts of copycat crimes.
- Pukosian Jackil - charged with contract killings from 57 planets and an attempted assassination of princess Io.
- Botsian Zortac - partnered with Sanoa and committed crimes under orders of Zindaze family.
- Thousanian Gineka - charged with running murder-game contest.
- Tenkaonian Raja Namunan - charged with 103 accounts of serial robberies-murders.
- Poppenian Hymal - a former Space Force scientist gone rogue.
- Mikean Clord - charged with serial murders of women from 7 ~ 8 planets.
- Aladonian Gyanjava - charged with murders, kidnappings of children and exploiting them to crimes, 3,000 accounts of robberies.
- Yuilwerian Mime - charged with violation of drug code, stealing women's souls with illegally made drugs.
- Guirarkian Don Bianco
- Zabunian Don Blaco
- Assassinian Jingi - charged with over 1,000 accounts of assassinations.
- Sumasuleenian Nikaradar - charged with murder, illegally producing dangerous life forms that resulted destruction of 7 planets.
- Bokudenian Biskes - charged with 999 accounts of murders in illegal duels.
- Sukekonoian Mashu - charged with marriage fraud and multiple murders of females.
- Dynamoian Terry X - charged with turning espers into batteries.
- Kulernian Jellyfis - charged with 214 accounts of murders, 673 accounts of thefts, complete submerging of 8 planets.
- Abrella's DekaBase Seizure Gang
- Gimonian Angorl
- Gedonian Uniga
- Dragian Ganymede
- Jergonian Sukeela
- Tylerian Durden - charged with running of illegal gambling, trading illegal substances and casualties caused by the said substance.
- Speckionian Genio - charged with kidnapping over 10,000 people from 124 planets, forcibly imprisoning them in Mirror World and depriving them of freedom.
- Ginjifuan Kazak
- Karakazian Don Sanoa - charged with blackmailing, kidnapping of law enforcement official, murders and assault under orders of Zindaze Family.
- Pyrian Kurachek - charged with 4170 accounts of arson; among them 27 accounts are planetary scale.
- Triggerian Buramudo
- Agent X
- Heavy Industrial Machines
- Machine Monster Gigas
- Space Life Form Browgouls
- Zoinaian Baytonin
- Slorpean Faraway
- Poppenian Hymal
- Falufian Yaako
- Kight Reidlich
- Bergian Kuronen
- Space Criminals Alienizer is the first group of Sentai Villains that are not a united organization and has no central leader, even though Agent Abrella is responsible for their atrocities by selling them machine.
- Alienizers are the first Heisei Sentai Monsters that does not grow gigantic themselves during their second phase of battle but pilot giant robots instead (in most of the cases). They are the second evil groups of Sentai franchise to have monsters of the week piloting a giant robot after Dark Science Empire Deathdark.
- However, exceptions exist, but have many diverse ways to grow, rather than having one object or agent doing the growing.