Bro's haire is a magnet 🧲
also Kerbals have massive heads with respect to their bodies, with roughly half of their total volume accounted for the head. Kerbal eyes protrude from their heads significantly, as do their corneas from the eyes. Kerbals appear to lack any irises, or they are perfectly black in color. They also possess no eyelids, and as a result do not blink.
Judging by official artwork and in-game models, Kerbals appear to have two large teeth that span the length of their gums, one on the mandible and one on the skull. However, this may be due to the cartoonish art style of the game and not actual fact. One of the load screen arts on the latest (1.x) versions of KSP shows Kerbals with multiple human-like teeth.
Their skin hues appear to range from light green to pale green, if they range at all. Although Kerbals appear mostly hairless, they have notable hair growth occurring on the top of their heads and Wernher von Kerman can be seen to have a mustache.
Kerbals also appear to be warm-blooded, given their ability to sweat, which is seen in the Asteroid Redirect teaser trailer on the KSP Youtube Channel.
Kerbals have an awkward, sprawling walk due to their wide pelvis and short legs. A Kerbal's walking speed on Kerbin is about 0.87 m/s, its running speed is about 2.35 m/s.
Anecdotal statements in the descriptions of the Rockomax HubMax Multi-Point Connector and the RoveMax Model XL3 suggest that Kerbals may die from shock when exposed to unexpected technological innovations. This could also be marketing hyperbole.
Kerbals seem to be in infinite supply, the in-game description of planet Kerbin saying its conditions support a "seemingly undepletable population of the eager green creatures".
Their most prominent personality traits are their Stupidity and Courage, as these are about the only individual traits to be seen beyond a name. Some Kerbals, such as Jebediah Kerman, have the rare "badass" trait, which makes them continually enthusiastic and without fear.
