My first name can be slighly confusing. I usually present myself as "Vašek", but you might have also seen me as "Václav". Both versions are just variants of a single Czech given name, both are correct.
What should you use?
In general, please use the name Vašek. For all legal and very formal purposes, use Václav.
It's ok to write both versions of the name without the accent marks.
|Google Translate link
Google Translate's TTS correctly pronounces my name when the language is set to Czech.
Why so complicated?
It's an old traditional Czech name and everyone in Czechia uses the diminutive form Vašek interchangeably with the formal version Václav. The situation is similar to the English name William and its form Bill.
I am actually not used to people calling me Václav, everyone just uses Vašek. And because foreigners usually struggle to pronounce Václav, I am just sticking with the informal version even in English.