Using the Dagger Symbol
The dagger, also called the obelisk, is a footnote reference mark and a typographic shorthand for "died". It is a narrow cross with a pointed foot, drawn to sit on the baseline at text size, which is what separates it from the religious crosses in the dingbat blocks.
The footnote sequence
When notes are marked with symbols instead of numbers, printers follow a fixed order on each page: asterisk , dagger †, double dagger ‡, section sign §, parallels ‖ and pilcrow ¶. A seventh note starts the sequence again with doubled marks (*, ††, ‡‡). The dagger is therefore the mark for a second note, and the double dagger for a third; you should never use † for a first note unless the asterisk is already taken by something else, such as a significance level in a statistics table. The sequence survives in many scientific journals for table footnotes, in the Chicago Manual of Style and in older reference works.
Death and extinction
In biographies, encyclopaedias and family trees the dagger before a date or a name means "died": Johann Sebastian Bach (\ 1685, † 1750)*. The asterisk is "born", which is why the two marks are usually seen together in German and Scandinavian reference books. Biologists borrow the same idea and put † in front of an extinct genus or species in a classification list, and sports lists mark deceased players the same way. Nothing religious is implied by the mark; it is simply a convention.
Mathematics and physics
Quantum mechanics writes the Hermitian adjoint of an operator as A† (read "A dagger"), and linear algebra uses it for the conjugate transpose. Chemists mark a transition state with a double dagger ‡. In these contexts the mark is a superscript, and LaTeX gives it with \dagger in math mode.
Lookalikes
The Latin cross ✝ and its shadowed cousin ✞ come from the Dingbats block; they are bigger, brighter and usually rendered in colour or with emoji styling on phones. If you need the proper typographic mark, use the dagger from General Punctuation; if you want an obviously religious or decorative cross, the cross symbols page collects the alternatives.
Gothic bios and usernames
The dagger has been a staple of alternative aesthetics since the Tumblr era. It brackets display names (†nyx†), decorates goth, metal and witchy Instagram bios and shows up in Discord tags beside gothic fonts and blackletter lettering. It renders in almost every font because the General Punctuation block is standard, and it passes the character filters on most platforms that allow anything beyond letters. Pair it with the section symbol or pilcrow if you want the whole "old manuscript" set.