Vlasák (feminine Vlasáková) is a Czech surname denoting a person with a large amount of hair (). Notable people include: Hana Vlasáková, Czech volleyball player Jan Vlasák (1943), Czech actor, famous for his role in the 2005 film Hostel Jerry Vlasak, American animal rights activist Lavínia Vlasak, Brazilian actress Lenka Vlasáková, Czech actress Oldřich Vlasák (1955–2024), Czech politician Oldřich Vlasák (wrestler), Czech wrestler Tomáš Vlasák, Czech ice hockey player
Wlassak is a Germanized version of the surname. Rudolf Wlassak, Austrian physiologist