Chris

Chris is a short form of the forename Christopher. There are two main types of such shortenings: they are convenient for writing, e.g. in lists; or they are essentially spoken pet-names, and thus informal. (See Conventional abbreviations for forenames.)

Short form	Long form	Informal or written	Other short forms	Remarks
Chris	Christopher	written AND informal	Kester, Kit	Chris is sometimes used for the female name Christina

There is a list of similar names at Conventional abbreviations for forenames, as well as the category:short names

Note that any informal form may be spelled in different ways. Notably, any spelling listed that ends in '-ie' may be written with the ending '-y', and vice versa.