The 7 are: Batman, Jim Gordon, Catwoman, Robin, Batgirl, Nightwing, and Talia al Ghul. Joker and Harley Quinn are separate Mayhem Collection DLC - not hidden story unlocks. Alfred and Lucius appear in short story beats only and never stay on the roster. Variety comes from 100+ suits, not more heroes.

1Unlock Order - Play the Chapters, Don't Grind

CharacterUnlocksGadgets
BatmanPrologue / Ch. 1Batarang, Batclaw, explosive gel, vision modes
Jim GordonChapter 1Foam Sprayer, Rebound Launcher
CatwomanChapter 2Whip, Call Kitty
RobinChapter 3 (Haly's Circus)Birdarang, Cable Launcher
BatgirlChapter 4Hackarang, Drone
NightwingChapter 4Electrorang, Electric Cable Launcher
Talia al GhulChapter 5Blowdarts, Ninja Dash
There is no character shop. No "buy 80 minifigs from the Batcomputer" loop. Side missions unlock suits, not extra people. If a puzzle is locked, you are missing a chapter character - not a secret extra.

2Gadgets Are Keys - Match Them to the Puzzle

Open-world and mission puzzles light up in detective vision with the character you need. Players keep getting stuck because they stay on Batman.

GordonFoam gums pipes and machines; bouncing explosive shots
CatwomanWhip pulls, cat distraction, vents
RobinMulti-target throw, walkable cable
BatgirlHacking panels, drone
NightwingElectric cable, shock throws
TaliaShort dash, blowdarts, ninja gaps
BatmanExplosive gel, Batclaw pulls, vision modes
Stuck puzzle tip: if Batman's AI walks off a button when you aim (common in Ace Chemicals-style puzzles), swap who you control, stand on a different platform, or pulse detective vision so the AI holds the switch.

3Decision Points That Actually Matter

Who to level first: WayneTech / skill points into Batman first, then whoever's gadget you just unlocked. Batman is forced into the party and is the best combat character; the others exist to open the map. Talia is easy to neglect - she arrives late and is gone for a long story stretch.
Suits vs characters: the 100+ suits come from story, open-world puzzles, Bat-Mite shops, and some account / preorder / LEGO-set codes. Empty display slots for paid extras are normal - they do not mean a missing playable character.
Co-op: Player 1 is locked to Batman by design. A local co-op screen-swap glitch let P1 leave Batman, but the July 17 patch closed it - don't plan a "swap to anyone" co-op session.
DLC: want Joker / Harley? That's the Mayhem Collection, not a late-game unlock. Base-game 100% does not require them.

Common Mistakes

See the Roster

All characters & suits (timestamps per hero):

All suits unlocked for all 7 characters: