| Arnold Timothée de Lasaulx | |
| Office: | 1st Mayor of Neutral Moresnet |
| Term Start: | 1817 |
| Term End: | 2 February 1859 |
| Predecessor: | Position established |
| Successor: | Adolf Hubert van Scherpenzeel-Thim |
| Birth Name: | Arnold Timothée Albert Francois Joseph de Lasaulx |
| Birth Date: | 1774 1, df=yes |
| Birth Place: | Castle Alensberg, Belgium |
| Nationality: | Belgian |
| Spouse: | Anne-Dorothe-Antoinette-Josphine de Braumann |
| Children: | 6 |
Arnold Timothée Albert Francois Joseph de Lasaulx (21 January 1774 – 18 July 1863[1]) was a Belgian politician who served as the first Mayor of Neutral Moresnet from 1817 until 1859. Having served for more than 41 years, he was Neutral Moresnet's longest-serving mayor, having served for nearly half of the territory's existence.
Lasaulx was born at Castle Alensberg, the son of Pierre-Olivier-Albert-Georges-Joseph de Lasaulx and Marie-Anne-Emérantiane-Josèphe de Mylius.[2]
He married Anne-Dorothée-Antoinette-Joséphine de Braumann, with whom he had six children:
He was a knight of the Austrian Order of Leopold and was awarded the Prussian Red Eagle Order, third class.
From 1817 to 1859 he was Mayor of Neutral Moresnet.