Dejdar is known for his numerous starring roles both comedic and dramatic in theatre, television and film.[2]
A hard-working method actor[3] known for his resolute devotion and research for his roles,[4] Dejdar is considered to be one of the most prominent actors of his generation.[5][6]
Since his debut in 1979, he has amassed over one hundred television and film credits.[7] His lead film roles in Why?, Big Beat and The Manor made him a household name in the Czechoslovakia.[8][9][10] He also portrayed Karl Rossmann in the Czech adaptation of Kafka's novel Amerika. He won the 1995 Czech Lion for Best Actor, for his performance in the film Učitel tance.[11]
He played Ozzak in the sitcom Comeback, starring with Tomáš Matonoha. In 2017, he participated in the reality show Tvoje tvář má známý hlas, the third season of Czech version of Your Face Sounds Familiar. After the 12 weeks, he placed 5th. He returned as the guest judge in the second episode of the fourth season.