Although Agents of S.H.I.E.L.D.’s future is still uncertain, the show has just passed its milestone 100th episode. As with many TV shows, S.H.I.E.L.D. took the opportunity to step back in time, to explore its own rich history, and to reintroduce a few familiar faces.

It did this with a clever narrative device, with a dimensional tear opening to a Dimension of Dreams - and nightmares. Coulson wound up facing off against some very familiar faces, but thankfully he was able to call in an old friend for help. So here’s a run-through of every character and concept that returned in “The Real Deal.”

Deathlok

The most notable cameo was from J. August Richards, reprising the role of Mike Peterson. Peterson was introduced in the pilot episode as an enhanced being who was gradually transformed into Hydra’s Deathlok soldier. He was freed from Hydra’s control at the end of season 1, and since then has helped the team out a couple of times. Fans have long hoped to get an update on Deathlok, so it was certainly exciting to see him back in action.

In a creative twist, Richards played two roles - including the manifestation of Coulson’s fear. Taking the form of Mike Peterson, the Dimension of Dreams taunted Coulson with the possibility that his “second chance” was just a figment of his imagination.

Hive

After all the trailers and teaser comments, the monstrous Inhuman known as Hive only made the briefest of cameos. Banished from the Earth for millennia, Hive was the main villain of season 3. The creature possessed the body of S.H.I.E.L.D. agent Grant Ward, effectively making this a double return.

It makes sense for Hive to number among the S.H.I.E.L.D. team’s greatest fears. The creature was only able to possess Ward because Coulson killed him on the planet Maveth; it was an act of revenge that would haunt Coulson through Season 3. Meanwhile, Hive was able to use its powers to enslave Daisy to its control, essentially reducing her to an addict needing her next fix.

The D.W.A.R.F.s

Back in Agents of S.H.I.E.L.D. Season 1, the D.W.A.R.F.s were FitzSimmons’s signature tech. These eight drones possess a sophisticated network of sensors, and were used by the scientists to explore and gather data. They’ve actually only appeared twice since season 1, used to investigate an Inhuman city and Endotex Labs. Evidently Fitz still has access to the D.W.A.R.F.s, though, as he used them to scout the damaged Lighthouse.

The Kree

There’s a brief, albeit brutal, scene with a Kree hunter. The Kree have most certainly become one of S.H.I.E.L.D.’s most dangerous foes. Coulson and his team first came across a live Kree when one traveled to Earth in season 2, seeking to kill Daisy. More Kree were drawn to Earth by Hive in season 3, and were slaughtered by the monstrous Inhuman. More recently, of course, the S.H.I.E.L.D. team have visited a dystopian future ruled by the aliens.

It’s uncertain whether the Kree was a manifestation of Daisy’s fears, or Deke’s. To Daisy, they’re a symbol of death, and the horrors that the future may hold; to Deke, they’re rulers of the oppressive reality he grew up in.

Lash

Season 3 saw Agent May suffer heartbreak when her ex-husband, Andrew Garner, was transformed into the monstrous being known as Lash. Driven with a desire to hunt down and kill Inhumans, Lash proved to be a fearsome adversary. The creature was ultimately killed in battle with Hive.

It’s safe to say Lash is drawn from May’s memories; Garner’s fate was one of the most painful experiences of May’s life.

LMD Simmons

Finally, in a callback to season 4, there’s a disturbing scene in which a version of Simmons actually attempts to kill Yo-Yo. This horrific version of Simmons is a manifestation of Yo-Yo’s fears, given a dark twist when she is revealed to be a Life Model Decoy. It’s artistically done, and a reminder that S.H.I.E.L.D. is essentially a superhero spy series; no-one is necessarily what they seem to be.

MORE: Agents of SHIELD Confirms Major FitzSimmons Fan Theory

Agents of S.H.I.E.L.D. continues Friday March 16th with “Principia” at 9pm on ABC.