Jan Kociniak was born in Stryj, Poland (now Ukraine). He graduated from The Warsaw Higher Theatrical School in 1961 and for most of his professional career, he acted in The Atheneum Theatre in Warsaw. He was also well known for his performances in features and TV films, as well as dubbing roles (such as Winnie the Pooh in the Polish-language version [its role taken over by another Polish voice actor, Maciej Kujawski], Mr. Spacely from Hanna-Barbera's The Jetsons & Willy [polish: Gucio] from Maya the Bee [main character was voiced by Ewa Złotowska]).
Kociniak was awarded the Order of Polonia Restituta, one of Poland's highest Orders.
Jan Kociniak died on 20 April 2007 from cancer. He was 69 years old.
- 1966: Winnie the Pooh and the Honey Tree - Winnie the Pooh
- 1968: Winnie the Pooh and the Blustery Day - Winnie the Pooh
- 1974: Winnie the Pooh and Tigger Too! - Winnie the Pooh
- 1977: The Many Adventures of Winnie the Pooh - Winnie the Pooh
- 1977: The Rescuers - Bernard
- 1987: A Muppet Family Christmas - Waldorf
- 1988-1991: The New Adventures of Winnie the Pooh - Winnie the Pooh
- 1990: The Rescuers Down Under - Bernard
- 2000: The Tigger Movie - Winnie the Pooh
- He voiced Winnie the Pooh in the Polish dubbing version of Cartoon All-Stars to the Rescue, which stars other Polish voice actors: Wiesław Michnikowski, Miriam Aleksandrowicz, Joanna Wizmur, Ilona Kuśmierska, Mieczysław Gajda, Krzysztof Tyniec, Mirosław Wieprzewski, Jacek Czyż, Włodzimierz Press & Zbigniew Suszyński.