French ….
If you are looking for someone in particular, post the info that you have and I can try to find him.
If you like searching, here are a few resources that I have used.
digitized matricules (by unit, does not include officers) :
"Les sous-séries GR 20 YC et GR 21 YC dont on trouvera ici la reproduction numérique recensent les sous-officiers et la troupe de la garde impériale et de l'infanterie de ligne pour la période 1802-1815"
link
the above matricules indexed and searchable (partially complete) :
link
digitized dossiers of members of the Légion d'honneur (typically does *not* include non-French, general offocers and those who were killed or disappeared in action) :
link
chevaliers of the Ordre de Saint-Louis 1814-1830 (complete, I think) :
link
Medaille de Saint-Hélène (partially complete – this medalwas given to any veteran of the military of the 1st Empire who was alive in 1857 and applied for it)
link
For officers there were various listings by unit and/or senioity called "état militaire" :
army overall : 1789, 1793, 1802, 1804, 1819, 1820
artillery : 1805, 1811, 1815
génie : 1808, 1825
A website which has collected and digitzed many "contrôles" of various regiments (and other resources) – most of the data is about officers, there is little or no pattern as to what is or is not included, several different methods of data presentation, etc., etc. – so the site is *not* easy to operate
ancestramil.fr/terre.html
Large and (slowly) growing list of detailed regimental histories (lots of officer information, some on sous-officers and soldats, lots of uniform information):
link
There is also quite a bit of free transcriptions of the "actes" recording aperson's "état-civil" (birth, marriage, occupation, death) – varies by départment, often incomplete, sometines just a "tease" to get you to buy access behind a paywall (of which be very wary – often all you get is from books that you could have found online yourself).