All the best 404 pages normally have something that stands out. From animated illustrations to custom typography, having a visually appealing and catchy error page can delight your visitors. So when building your websites be sure not to forget to style them.
Bellow you will find a list I put together of some of the best 404 page template examples I could find on CodePen.
Construction Worker 404 Page
A creative 404 page template using a construction worker illustration looking left and right while being in a hole.

See the Pen Construction Worker 404 Page by mipz_ (@mipz_) on CodePen.
No Vacancy 404
This example was made using novacancy.js to test out a 404 page concept.

See the Pen No Vacancy 404 by rileyjshaw (@rileyjshaw) on CodePen.
Mars 404 Error Page
A cool Mars 404 error page using some excellent illustrations.

See the Pen Mars 404 Error Page by AsyrafHussin (@AsyrafHussin) on CodePen.
Record Disc 404 Page
A neat record disc illustration animated for a 404 error page. Great for music related websites.

See the Pen Record Disc 404 Page by Banny (@Banny) on CodePen.
CSS Train 404 Page
SVG 404 error page made with CSS only that depicts a moving train.

See the Pen CSS Train 404 Page by ckroll17 (@ckroll17) on CodePen.
404:Page Not Found
A 404 page that contains lighthouse illustration made with pure CSS animation. I will look great in a lot of website designs.

See the Pen 404:Page Not Found by Mitali96 (@Mitali96) on CodePen.
Summer’s 404 page
Awesome summer illustration perfer for a 404 error page.

See the Pen Summer’s 404 page by BlackStar1991 (@BlackStar1991) on CodePen.
Skew Maker Text 404 Page
A cool 404 error page that uses skewed marker text.

See the Pen Skew Maker Text 404 Page by lizponce (@lizponce) on CodePen.
Game Illustration SVG – 404 Page
Beautiful SVG illustration animated with CSS. Works great for a game’s 404 page.

See the Pen Game Illustration SVG – 404 Page by thejohnyagiz (@thejohnyagiz) on CodePen.
Science 404 Page
Simple animated 404 page for a startup I'm working with.

See the Pen Science 404 Page by saransh (@saransh) on CodePen.
Sudoku 404 Page Not Found
A Sudoku inspired 404 error page. Works for almost any type of website/

See the Pen Sudoku 404 Page Not Found by gavra (@gavra) on CodePen.
404 Particle Text Effect
PIXI experiment “404 not found page” particle text.

See the Pen 404 Particle Text Effect by enricotoniato (@enricotoniato) on CodePen.
Pure CSS 404 Error Page
Pure CSS 404 Error Page with css animation

See the Pen Pure CSS 404 Error Page by sqfreakz (@sqfreakz) on CodePen.
404 Page Based On A Dribbble Shot
404 error page based on a Dribbble shot https://dribbble.com/shots/2082597-404-Page

See the Pen 404 Page Based On A Dribbble Shot by iremlopsum (@iremlopsum) on CodePen.
404 Page Animation
404 error page animation inspired by: https://dribbble.com/shots/2318674-404-Screen

See the Pen 404 Page Animation by THEORLAN2 (@THEORLAN2) on CodePen.
Black Hole 404 – Lost In Space
A simple 404 with a cool spaceship animation.

See the Pen Black Hole 404 – Lost In Space by kylelavery88 (@kylelavery88) on CodePen.
BIOS Style 404 Page
A BIOS like 404 page using some SCSS.

See the Pen BIOS Style 404 Page by igloude (@igloude) on CodePen.
404 SVG Animated Page Concept For Zajno eStore
This SVG was created for an e-store, a project for Zajno.

See the Pen 404 SVG Animated Page Concept For Zajno eStore by gxash (@gxash) on CodePen.
Science & Education 404 Page
A trendy 404 page that works great for youthful websites.

See the Pen Science & Education 404 Page by jaymierosen (@jaymierosen) on CodePen.
404 Error Example
From graphic design to web design. This 404 error example was designed by Yoga Perdana and we have converted into web with pure CSS and minimal HTML using CSS3 gradients and shadows. See more creative examples in the related pens.

See the Pen 404 Error Example by ricardpriet (@ricardpriet) on CodePen.
Bubbley 404 Page
A Material Design 404 error page with lots of bubbles.

See the Pen Bubbley 404 Page by kylelavery88 (@kylelavery88) on CodePen.
Lost In Space 404 Page
Space exploration 404 page based on Dribbble shot: https://dribbble.com/shots/4330167-404-Page-Lost-In-Space

See the Pen Lost In Space 404 Page by salehriaz (@salehriaz) on CodePen.
Lost On Sea 404 Page
Isolated island with a floating boat illustration perfect for a 404 page.

See the Pen Lost On Sea 404 Page by androhani (@androhani) on CodePen.
Error 404 with pure CSS: Monument Valley Inspiration
I entered the Up Labs Challenge for 404 pages and I made this Monument Valley inspired illustration using only CSS.

See the Pen Error 404 with pure CSS: Monument Valley Inspiration by sus-casasola9210 (@sus-casasola9210) on CodePen.
Yeti 404 Page
A cool scarry night 404 page with a yeti using a flashlight.

See the Pen Yeti 404 Page by dsenneff (@dsenneff) on CodePen.
Prehistoric 404 Page
A funny 404 page depicting a prehistoric man getting electrocuted.

See the Pen Prehistoric 404 Page by Navedkhan012 (@Navedkhan012) on CodePen.
GSAP: SVG Animation 404 Error Milk Carton
A 404 milk carton page great for drink related websites.

See the Pen GSAP: SVG Animation 404 Error Milk Carton by christinei (@christinei) on CodePen.
Ghost 404 Page
404 error ghost page! Animated pure css ghost with search bar & buttons to go back home!

See the Pen Ghost 404 Page by juliepark (@juliepark) on CodePen.
No Connection Error Page
“Your devices are unplugged” error page.

See the Pen No Connection Error Page by kylelavery88 (@kylelavery88) on CodePen.
Beer Bottle 404 Error
A little 404 error doodle w/SVG and clip-path animation inspired by a recent client project for a brewery.

See the Pen Beer Bottle 404 Error by chadamski (@chadamski) on CodePen.
404 Page – Frog Illustration
A cute little frog animation sitting on a 404 block.

See the Pen 404 Page – Frog Illustration by IrisTips (@IrisTips) on CodePen.
Crying Baby 404 Page
404 error page in pure CSS3. Character inspired from Arturo MB's Cry Baby

See the Pen Crying Baby 404 Page by vineethtr (@vineethtr) on CodePen.
404 Page – Tentavle SVG Illustration & Animation
Inspired by: https://dribbble.com/shots/1869337-404, this 404 page depicts a bottle floating above a pair of tentacles.

See the Pen 404 Page – Tentavle SVG Illustration & Animation by anycircle (@anycircle) on CodePen.
404 Page – Animated Robot
A cute white robot with a 404 written on it.

See the Pen 404 Page – Animated Robot by turpoint (@turpoint) on CodePen.
SVG Animation 404 Page
SVG Animation to create an error page 404. Use the library SnapSVG.

See the Pen SVG Animation 404 Page by Stephane (@Stephane) on CodePen.
Moon Illustration – 404 Error
This 404 page depicts the Moon with a red 404 flag.

See the Pen Moon Illustration – 404 Error by ddly (@ddly) on CodePen.