Sommer was born in
Germany, to a German-born
Greek father, from
Crete, and a
German mother. Sommer spent most of his childhood years in
Germany and later moved to
Greece. Sommer attended the
German School of Athens. He was bitten by the acting bug as a young boy and continued working in television and film in Greece. He started modeling at age 12 and graduated of
UCLA (Arts and Psychology) in 1997. He is a very well known Greek celebrity appearing in numerous magazines and commercials before participating in big screen film productions such as
Brides by
Pantelis Voulgaris, The Boston Strangler, ''A Breath's Distance
, Golden Beach and Extreme Sommer.
Some of his television credits include Love Came From Afar
, Soko Germany.
He has also appeared in several Broadway plays include playing the part of Joe Bonaparte
in Golden Boy and Liliom
. He enjoys extreme sports as well as skydiving, jetski, speed boat, car and motorcycle racing/stunts. He currently lives between Athens and Los Angeles. He was starring in the Greek TV series Tis Agapis Maheria
(), (The Knives of Love
) by Stratos Markidis'' for
ANT1. This series had a personal connection to Kostas since the story is based in Cretan traditions. Kostas is also a very renowned lobbyist, active in the political as well as the business genre with many substantial deals and connections to his name. In 2019 he ran for a member of the European Parliament, and in 2023 for Regional Councillor for the Region of Attica. ==Personal life==