How to insert a trademark symbol? (tm)

Package textcomp adds symbols with TS1 encoding and provides symbol \texttrademark:

\documentclass{article}
\usepackage{textcomp}

\begin{document}
\textsuperscript{TM} or \texttrademark
\end{document}

Note that LaTeX supports and shows correctly also the ™ character.

(tested with \usepackage[utf8x]{inputenc})