Mouthplate

I am smiling on the outside, but crying on the inside... not that you could tell anyway.

Instead of regular human facial features, some Transformers have what looks like a plate affixed to their lower jaw, usually covering up to their nose. While no official name exists for these, they are usually called 'mouthplates ' or 'faceplates' (despite a 'regular' face once being described as a faceplate in the TV series). Two of the most famous examples are those of Generation 1's Optimus Prime and Soundwave. Sufferers of Primus apotheosis often affix themselves with unnecessary faceplates to better emulate their idol.

In earlier series, a Transformer's mouthplate moved when they spoke, as if there were a working jaw underneath. In later series such as Victory, Robots in Disguise and the Unicron Trilogy, however, it remains static.

Certain Transformers who sport mouthplates do have regular mouths underneath. Sometimes these mouthplates are even retractable, either in full or partially, to reveal their mouths.

Fiction/Toylines

Generation 1 continuity

Optimus Prime featured a prominent mouthplate in both cartoon and toy form (as do all other G1-based toyline versions). The 20th Anniversary figure featured a mouthplate that was movable via a button on the back of his head that slightly lowered the spring-supported mouthplate to recreate the talking action seen in the cartoons.

Soundwave had a similar mouthplate, but no apparent nose (whether any of his assumed face was visible or not is debatable, considering how visor-esque his eyes were). Like Optimus, both his cartoon and toy form had the mask. No toys have yet been made with a moving mask feature.

Wheeljack's mouthplate was unique in that it was fixed, even in the cartoon. Instead of a movable mouthplate, you knew Wheeljack was speaking because his "ears" flashed.

Many early toys had mouthplates that were simply disregarded in favor of mouths in fictional appearances (barring the occasional toy-accurate rendering). Bumblebee in particular had a mask in toy form, but not in cartoon or comic form. A rare reissue of the toy featured a cartoon-accurate face, however, as did most toys of him since. Conversely, as Goldbug, he featured a mask in both cartoon and toy form. On the other hand, Superion had a faceplate on the cartoon even though his toy had a mouth.

Ultra Magnus in his newly reborn body from the Japanese continuity also featured a mouthplate. Hybrid Style Convoy Black Version

Hot Spot sometimes had a mouthplate and sometimes he didn't.

Beast Wars

Optimus Primal was shown to have a mouthplate which would slide into place when he entered battle. This was used to reconcile the presence of an actual mouth on his animation model with the lack thereof on his toy. Later retoolings of the toy reflected the animation model.

Dreamwave comics continuity

25 years before someone realized his toy has no face.

In The War Within, Bumblebee was depicted as having a removable face mask with mouthplate that resembled the original sculpt of his toy. In The Dark Ages, Jetfire was given a similar treatment with a flip-up faceguard. The Titanium Series release of this character design featured the faceguard, but it was not removable. Brawn was depicted with a removable face mask like Bumblebee's in the ongoing Generation 1 series.

IDW comics continuity

In Stormbringer, Jetfire had a removable mask with mouthplate as part of his battle gear. This feature was included in the Classics toy of this character design. Most recently in All Hail Megatron, Optimus Prime himself revealed he has a retractable mouthplate much like his Movie counterpart. This would be the first time in an official story that the G1 version of the character is portrayed as being able to remove his mouthplate, revealing that he does have a mouth underneath it (which he used to eat some energon).

Robots in Disguise

Optimus Prime, X-Brawn, Prowl, Scourge and all of the Commandos bar Rollbar sported non-moving mouthplates.

Unicron Trilogy

In Energon, when Wing Dagger was killed by a falling Energon Tower, his mouthplate shattered, revealing a mouth beneath it. It's unclear whether all mouthplated Transformers in this continuity had similar setups.

In Cybertron, the Optimus Prime animation model displayed a similar setup to Optimus Primal, with a mouthplate that slid into place when entering Super Mode. However in this case the toy reflected this, featuring a gimmick that allowed the face to display either configuration.

Live-action Transformers movies

Megatron did that just to piss off the purists. He's that evil.

Optimus Prime was depicted as having a combat mouthplate which closed over his normal mouth to protect his face. To date, only one of Prime's Robot Heroes figurines, Buster Optimus Prime, and his two retooled Battle Hooks toys displayed his face and mouth, while all other merchandise featured the plate. Blackout also had a mouthplate, seen very briefly. Bumblebee had two pieces that rest on the top of his head normally but slide down and clamp together over his whole face in battle. Bumblebee's faceplate had a very insectoid appearance, crediting his name. Jazz had a visor that protected his upper-face in combat. Ironhide also had a mouthplate similar in appearance to Optimus Prime's as shown in some of his concept art and toys, however he has never officially used it on film.

In Revenge of the Fallen Optimus Prime's faceplate was smashed to pieces when he was kicked in the face by Megatron, but it was replaced when he combined with Jetfire. While not noticeable in the film, Sideswipe's Human Alliance toy confirmed he had an extra layer of armor plating (which was thought to be his actual face) protecting his main face.

Transformers Animated

Most of the Autobots in Optimus Prime's crew had retractable faceplates. Optimus, Bumblebee, Sari and Prowl each had one. Sentinel Prime had one, too, though his was unique in that it covered his whole face. Among the Decepticons, Soundwave had a non-retractable mouthplate, much like his G1 predecessor's. Optimus's mouthplate flapped up and down when he talked, just like that of G1 Optimus, but none of the others' did.

Transformers Prime

Optimus Prime and Wheeljack each had a mouthplate that they slid into place over their faces whenever they entered battle. Nemesis Prime, being a copy of Optimus, had a mouthplate too, though it was permanently deployed.

Notes

• Fan commentator Zobovor nicknamed these distinctive items "woobers" (crediting the term to a younger relative), and the name became popular with some fans.
• Both the Armada Optimus Prime and the 20th Anniversary Optimus Prime toys have mouthplates that can move up and down when a button located on their heads is depressed, even though Armada Prime's mouthplate never moved in the series itself. Additionally, the 20th Anniversary toy has teeth (or possibly a speaker grille) hidden behind the mouthplate, in reference to Optimus Prime's battle-damaged appearance in the Generation 2 comics, though this detail cannot be seen without disassembling the entire head (or just looking down with it pulled down really far).
• The lack of a full-time mouthplate on certain characters has, in the past, been known to result in certain reactions from the fandom. Oh well.