Within the Ultra Series's long run, there have been numerous:
Showa
- The original series had Alien Zetton (not the monster who served as the Final Boss, but its creators).
- Ultraman Ace's Yapool was the first individual one.
- Ultraman Leo's final 12 episodes introduced Commander Black and the Black Star, a sentient planet that creates Flying Saucer kaiju.
- Ultraman 80 has the Minus Energy, though it's more a Sentient Cosmic Force than a tangible character.
- The movie Ultraman Story had Juda, who was first introduced in the Andro Melos miniseries (see below).
Heisei
- Ultraman Tiga gave us the Eldritch Abomination Gatanozoa.
- The Movie Ultraman Tiga: The Final Odyssey has Camila, leader of the evil Ultramen called the Dark Giants.
- Ultraman Dyna has the Gransphere.
- Ultraman Gaia referred to something called the Radical Destruction Bringer, a cosmic force/entity/something that sought to destroy Earth. However, its identity is very intangible, so most fans will cite Zogu instead.
- Ultraman Cosmos had Chaos Header. The Movies featured Basical (Ultraman Cosmos: The First Contact), then Sandros (Ultraman Cosmos 2: The Blue Planet), and then Delaxion (Ultraman Cosmos vs. Ultraman Justice: The Final Battle).
- Ultraman Nexus had the evil Ultraman clone, Dark Zagi.
- The prequel movie, Ultraman: The Next, had The One, the first of the Space Beasts to attack Earth.
- Ultraman Mebius has several villains take the role for a time, but in the end it's revealed all of them were working for Alien Empera in some way.
- Ultraman Mebius and the Ultra Brothers has Yapool, who also returns in the series as one of Empera's 4 Heavenly Kings, but gets to be Big Bad in The Movie.
- Superior Ultraman 8 Brothers had Super Alien Hipporit though he was really a creation of the Black Silhouettes.
- Ultraman Mebius Gaiden
- Hikari Saga has Alien Babalou.
- Armoured Darkness has the titular Armoured Darkness, an Animated Armour Alien Empera left behind.
- Ghost Reverse has the Four Heavenly Kings, with Alien Empera as a Greater-Scope Villain they seek to revive.
- Ultraman Zero
- Mega Monster Battle: Ultra Galaxy Legends had Ultraman Belial.
- Ultra Galaxy Legend Gaiden: Ultraman Zero vs. Darklops Zero has Darklops Zero, though it's later to be but one of many Mooks in the army Belial was building up between movies.
- Ultraman Zero: The Revenge of Belial had Belial again, back as Kaiser Belial.
- Ultraman Saga had Alien Bat and his monster Hyper Zetton.
- In his various other materials, it usually alternates between Belial and Bat.
New Generation
- Ultraman Ginga had Dark Lugiel.
- The sequel series, Ultraman Ginga S had an Alien Chibu named Exceller until Lugiel is resurrected and kills him.
- Ultraman Ginga S The Movie: Showdown! The 10 Ultra Warriors!'s villain was Etelgar.
- Ultraman X gives us Greeza.
- Ultraman X The Movie: Here Comes! Our Ultraman! has Zaigorg.
- Ultraman Orb's villain is Jugglus Juggler, though the bigger story that's All There in the Manual has him as The Rival instead.
- In Ultraman Geed, Ultraman Belial returns as the Big Bad, though Kei Fukuide is his Dragon-in-Chief. The Movie has Gilvalis.
- Ultraman R/B begins with Cereza (possessing the body of Makoto Aizen) before Saki Mitsurugi takes over in episode 16. Ultimately though, the true villain of the series reveals itself to be Reugosite.
- Ultraman R/B The Movie: Select! The Crystal of Bond introduces Ultraman Tregear, who is also the Greater-Scope Villain of the series itself by virtue of corrupting Reugosite. He later goes on to become the Big Bad of the succeeding series, Ultraman Taiga.
- Ultraman Z has Celebro.
- Ultraman Trigger: New Generation Tiga has Carmeara, leader of the Dark Giants.
- Ultraman Decker has the Mother Sphere, later Mother Spheresaurus, the Spheres' creator and commander.
Reiwa
- Ultraman Blazar has Varallon, a genocidal kaiju overlord sent by the V99 aliens as retaliation for the major incident years before the series' events which brought the titular Ultra to the human world. Despite his employers standing down peacefully, he does not and remains the main threat from beginning to end.
Spin-offs
- The obscure 1983 spinoff Andro Melos had the Evil Overlord siblings Gina, Judahnote , and Mold. The Terrible Trio return with a secondary role in Ultraman X.
- Ultra Galaxy Mega Monster Battle had the Alien Pedans' leader, Harlan. Another was later revealed though: Reiblood, who is expanded to the Greater-Scope Villain of the Ultraman Zero instalments.
- Ultra Zero Fight has the Darkness Five in a duumvirate case, though it's later revealed they're all minions of Ultraman Belial.
- Ultra Fight Victory had Yapool, seeking to revive the aforementioned Juda.
Non-Japanese Series
- Ultraman: Towards the Future: The Gudis virus, although only for the first 6 episodes. The remaining 7 focus more heavily on the Green Aesops.
- Due to being essentially an Americanized remake of the original Ultraman, Ultraman: The Ultimate Hero uses his most famous foes, the Baltans, as the main villains.
