Comic Sans MS is a sans-serif typeface created and designed by Vincent Connare and released by Microsoft Corporation in 1994. Designed as a non-connecting script, the typeface draws inspiration from comic book lettering, to emulate the informal and cartoonish tone of speech bubbles. It was originally developed for use in Microsoft's software, and since then has become widely recognized for its use in casual contexts such as children's books, personal documentation and in educational resources.

The typeface was first introduced with Microsoft Windows as a part of the Microsoft Plus! Pack, and was later implemented into Microsoft Comic Chat as a comic styled chat application. Since then, Microsoft has described the font as "casual and legible" and a typeface which has garnered much popularity across a diverse set of user groups.

Comic Sans has however become a cultural phenomenon, in part due to gaining significant criticism and mockery for its perceived overusage and misuse in professional and formal settings. Despite this, the typeface continues to hold a cult following, particularly among education professionals and those in search of approachable and simplistic typefaces for specific uses.

Microsoft designer Vincent Connare began working on Comic Sans in 1994 after having already created other fonts for various applications. When he saw a beta version of Microsoft Bob that used Times New Roman in the word balloons of its cartoon characters, he believed the typeface gave the software an overly formal appearance. He believed this was inappropriate for the aesthetics of the program, which was created to introduce younger users to computers. In order to make Microsoft Bob look more suitable for its intended purposes, he decided to create a new typeface with only a mouse and cursor, based on the lettering style of comic books he had in his office, specifically The Dark Knight Returns (lettered by John Costanza) and Watchmen (lettered by Dave Gibbons).

He completed Comic Sans too late for inclusion in Microsoft Bob, and the typeface would go unreleased until the programmers of 3D Movie Maker, which also used cartoon guides and speech bubbles, adopted it. The speech bubbles were eventually phased out and replaced by actual sound, but Comic Sans stayed for the program's pop-up windows and help sections. The typeface later shipped with the Windows 95 Plus! Pack, and was the primary font of the Travel desktop theme. It was later included as a system font for the OEM versions of Windows 95. Finally, it became one of the default fonts for Microsoft Publisher and Microsoft Internet Explorer. Comic Sans is also used in Microsoft Comic Chat, which was released in 1996 with Internet Explorer 3.0.

Comic Sans is pre-installed in macOS and Windows Phone, but not Android, iOS or Linux. Comic Sans can be manually downloaded on iOS.

Comic Sans Pro is an updated version of Comic Sans created by Terrance Weinzierl from Monotype Imaging. While retaining the original designs of the core characters, it expands the typeface by adding new italic variants, in addition to swashes, small capitals, extra ornaments and symbols including speech bubbles, onomatopoeia and dingbats, as well as text figures and other stylistic alternatives. Originally appearing as part of Ascender 2010 Font Pack as Comic Sans 2010, it was first released on April Fools' Day, causing some to initially assume it was a joke.

The italicized variant later appeared in Windows 8.