In the RIPE community, Ondřej serves as one of the RIPE Arbiters.
In the DNS community, Ondřej is one of the DNSOP working group chairs at IETF and at ICANN, he is also the Recovery Key Share Holder for the Root Zone keys ceremony and member of the Registry Services Technical Evaluation Panel.
Outside of the RIPE community, you might know Ondřej as the Debian Developer who maintains PHP directly in Debian and through the deb.sury.org project, also provides the PHP packages for various PHP versions and various Debian and Ubuntu distributions.