The “ Comprehensive symbol list”, lists the symbol commands `\``textcopyright`, `\``textregistered` and `\``texttrademark`, which are available in TS1-encoded fonts, and which are enabled using the textcomp package.
In fact, all three commands are enabled in default LaTeX, but the glyphs you get aren’t terribly beautiful. In particular, `\``textregistered` behaves oddly when included in bold text (for example, in a section heading), since it is composed of a small-caps letter, which typically degrades to a regular shape letter when asked to set in a bold font. This means that the glyph becomes a circled “r”, whereas the proper symbol is a circled “R”.
Another problem arises if you want `\``textregistered` in a superscript position (to look similar to `\``texttrademark`). Using a maths-mode superscript to do this provokes lots of pointless errors: you must use
```\textsuperscript{\textregistered}