Within the Ultra Series's long run, there have been numerous:
Showa
- Ultraman Ace's Yapool was the first 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.
- Its 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.
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.
