They are sometimes referred to as Panic Sections or Skirmishes.
Occasionally actual Core Ships and special enemies will appear mid-level - but this is rare for the Gradius series, and occurs more often in the Parodius Series series. The Parodius games and Gradius ReBirth are the only games to use separate music for Sub Boss battles. In most cases these sub boss battles occur directly before the stage boss.
This tradition started in the original game and has stayed ever since. Whilst many Sub Bosses in the first game have gone on to become traditions in the overall Gradius franchise, other games have introduced their own specialized enemy skirmishes.
Notable Sub Bosses:
- Volcano : Present in many games in the series, the volcano is a popular element.
- Zub Rush : Appearing in the majority of Gradius and Parodius games, the Zub Rush has become a staple in the Boss Rush levels, allowing the player to gain additional power up capsules.
- Iron Maiden : Recurring sub-boss that later showed up in Parodius Da! in a extremely difficult section of the game.
- Maru Maru : A one shot Sub Boss in Nemesis GB, that got expanded upon to form a fully fledged boss fight in Gradius ReBirth, the Moai Orb.
- Jumping Moai : `A sub-boss that showed up in nearly every port of Salamander, and got a significant health boost in the Commodore 64 version.
Stronger, singular versions of this boss show up in later games as well.
- Center Core : Starting off as a regular Boss in the first Salamander, this Gunwall got knocked back into being a Sub Boss in several ports.
|Sub Bosses / Panic Segements|
|Traditional / Recurring||Volcano • Zub Rush • Iron Maiden • Skeleton Wave • Center Core • Jumping Moai • Dogas|
|One Shot|| Mother and Child • Tentacle Golem • Iron Maiden MK 2 • Maru Maru • Statue Guardians • Asteroid Field • Prominence Zone • Block Core • Triple Core • Rotating Moai|