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 One's Soundwave and Optimus Prime.
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 moveable 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 is visible or not is debateable, considering how visor-esque his eyes are). Like Optimus, both cartoon and toy forms had the mask. No toys have yet been made with a moving mask feature.
Bumblebee had a mask in toy form, but not in cartoon nor comic form. A rare reissue of the toy features a cartoon-accurate face, however, as do most toys of him since. Conversely, as Goldbug, he featured a mask in both cartoon and toy form.
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.
The Optimus Prime animation model displays a similar setup to Optimus Primal, with a mouthplate that slides into place when entering Super Mode. However in this case the toy reflects this, featuring a gimmick that allows the face to display either configuration.
Dreamwave comics continuity
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 One series.
IDW comics continuity
Transformers (2007) film
Optimus Prime is depicted as having a mouthplate which closes over his normal mouth to protect his face. To date, only one of Prime's three Robot Heroes figurines displays his face and mouth, while all other merchandise features the plate. Ironhide also has a black mouthplate that looks EXACTLY like Optimus's old mouthplate. Blackout also has a mouthplate, seen very briefly. Bumblebee has 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 has a very insectoid appearence, crediting his name. Jazz has a visor that protects his upper-face in combat.
Most of the Autobots in Optimus Prime's crew have retractable faceplates. So far, Optimus, Bumblebee, and Prowl each have one. Sentinel Prime has one, too, though his is unique in that it covers his whole face. Among the Decepticons, Soundwave has a non-retractable mouthplate, much like his G1 predecessor's. Optimus' mouthplate flaps up and down when he talks, just like that of G1 Optimus, but none of the others' do.
Optimus Prime has a retractable faceplate much like the movie incarnation.
The Vehicons all have non-retractible mouthplates that cover their entire faces, assumming they have faces under them.
Less of a faceplate, Soundwave's face is a screen visor that displays wavelenghts of a voice recording or pictures (name another Transformer whose face can do that).
- 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).