Several dozen named colors start with E across the major catalogs — Wikipedia's color lists, Pantone, heritage paint references, historical pigments, and the xkcd Color Survey. This page currently lists 50 of the most widely-recognized of those, deduplicated by hex value. Notably, ZERO of the CSS Color Module Level 4 named-color keywords start with E — the W3C named-color list jumps directly from dodgerblue (D, #1E90FF) to firebrick (F, #B22222) with no E-named keyword in between. E is not unique in this respect: the CSS named-color list also has no keywords beginning with J, Q, U, X, or Z. The contrast with D (which has 21 CSS-named D-color entries, the most of any letter) is what makes the gap at E unusual rather than the gap itself.

A few make a strong case. Egyptian Blue is the earliest-known synthetic pigment in human history — used by ancient Egyptian artisans from around 3000 BC. Emerald was Pantone's Color of the Year for 2013 and remains one of the four cardinal precious gemstones (alongside diamond, ruby, and sapphire). Eigengrau is a beloved curiosity — the German "intrinsic gray" that vision scientists use to describe the dim gray your eyes perceive in absolute darkness, named in the 19th century by physicist Gustav Fechner. Eton Blue has been used by sportsmen of Eton College since the early 19th century. And Eagle Green is the community-database reference for the Philadelphia Eagles' Midnight Green team identity, in use since the franchise's 1996 rebrand.

The CSS named-color list (147 keywords, fixed by the W3C CSS Color Module Level 4 specification) was inherited largely from the X11 color set developed for the X Window System on Unix workstations, which itself grew from a list of color names in common use rather than a systematic plan. That informal origin is why the list has uneven letter coverage: it simply never included a keyword beginning with E (nor with J, Q, U, X, or Z), jumping from dodgerblue straight to firebrick. Most E-colors are either heritage compound names (Egyptian Blue, English Vermilion, Eton Blue), specific pigments (Emerald Green), or relatively recent additions (Electric Pink, Eerie Black) that were never part of that early list. The CSS spec preserved the gap when it inherited the X11 names; the only later addition to the spec was rebeccapurple (2014, in tribute to Rebecca Meyer), which did not change the E-gap.

Egyptian Blue is the earliest known synthetic pigment, used in ancient Egypt from around 3000 BC through the end of the Roman period in Europe. Chemically it is calcium copper tetrasilicate (CaCuSi4O10), identical in composition to the rare natural mineral cuprorivaite. It was produced by heating quartz sand, copper compounds (often the green mineral malachite), lime, and an alkali flux to around 850–950°C — a precise, repeatable procedure that required real chemical understanding at a time when most colors were ground from natural minerals. The ancient Egyptian name for it was hsbd-iryt, "artificial lapis lazuli," because it was developed as a cheap substitute for the precious blue stone mined in what is today Afghanistan. After the fall of Rome the recipe declined sharply in Europe and the pigment largely fell out of use; modern scientific study of it revived in the 19th century, after surviving samples were examined (notably blue unearthed at Pompeii). It did not vanish entirely, though — later analysis has found Egyptian Blue in some early-medieval and Renaissance works. In 2009 researchers discovered that Egyptian Blue has an unusually strong near-infrared luminescence, prompting research into potential applications such as biomedical imaging, security inks, and lasers (most still at the research stage rather than established commercial use).

Eigengrau (German for "intrinsic gray," also called Eigenlicht or "brain gray" in English) is the uniform dark gray that most people perceive when in absolute darkness — the color of true darkness as the human visual system actually experiences it. Even in the complete absence of light, retinal cells and the optic nerve fire spontaneously at a low baseline rate ("dark light" or "visual noise"); the brain interprets this baseline activity as a dim uniform gray rather than as absolute black. The term is generally attributed to the 19th-century German physicist and psychophysics pioneer Gustav Fechner (1801–1887), who observed in his perception experiments that test subjects in complete darkness still reported seeing something. Curiously, eigengrau appears lighter than a black object viewed in normal daylight, because the visual system processes contrast more sensitively than absolute brightness — which is why a night sky, broken by scattered stars, looks darker than the gray you see with eyes closed in pitch darkness.

Eton blue is a well-known case where the color name dramatically misleads about the actual color. The cataloged Wikipedia "List of colors" value (#96C8A2) is unmistakably a pale mint-green; even Eton College's own more-recent reference standard sits firmly in the green-leaning end of the spectrum, not in blue at all. The name dates to the early 19th century, when "blue" was being used loosely in British English to mean any of several pale, washed, cool shades — a usage echoed in the parallel Cambridge Blue (also a pale green-blue, used by the University of Cambridge). Chelsea Football Club wore Eton blue from its 1905 founding (Earl Cadogan, the club's president and an Old Etonian, supplied the color from his racing silks) before adopting the deeper royal blue still used today — the club's official history dates the change to 1907, though many kit historians put it around 1912. This page classifies Eton Blue under the "green" shade family, following its actual visual hue (the #96C8A2 swatch is a pale mint-green) rather than the "blue" in its historical name — the rendered plate makes the green character obvious at a glance.