Namesakes
Other Royalty:
1 prince
Johann II, Prince of Liechtenstein (a.k.a. Placidus) 1858-1929 Liechtenstein 
Saints:
4 saints
Saint Eustace (a.k.a. Placidus) ?-118
Saint Placidus ?-3xx
Saint Placidus ?-541
Saint Placidus of Autun ?-675