He escaped the Emslandlager labor camp near Papenburg by disguising himself as one of the German officers, a role he would later play so often on both big and small screens.

Though he appeared in many European films, van Dreelen is best remembered as an A-list guest star in dozens of American television shows from the early 1960s to the mid-1980s, such as 12 O'Clock High, The Twilight Zone ("The Jeopardy Room"), The Man from U.N.C.L.E., Voyage to the Bottom of the Sea, The Wild Wild West, Combat!, Blue Light, Mission: Impossible and Wonder Woman.

"[7] Never a major player in theatrical films, he nonetheless scored a few choice roles, including the Danish concert pianist who rescues and woos Lana Turner during an extended sequence in Madame X in 1966.

[8] Four episodes of Blue Light were edited together to create the theatrical film I Deal in Danger, which was released in December 1966 and included his appearance.

[9] His other film credits included roles in Von Ryan's Express (1965), Topaz (1969), Lost Horizon (1973), The Big Game (1973), The Clone Master (1978), The Formula (1980), The Money Pit (1986) and Born to Fight (1989), as well as TV miniseries such as The Rhinemann Exchange, The Word and Washington: Behind Closed Doors.