unmarked footnote
\documentclass{article}
\usepackage{lipsum}
\newcommand\blfootnote[1]{%
\begingroup
\renewcommand\thefootnote{}\footnote{#1}%
\addtocounter{footnote}{-1}%
\endgroup
}
\begin{document}
Some text\blfootnote{A footnote without marker} and some more text\footnote{A standard footnote}
\end{document}