They were named after Lieutenant Wilbur Clingan, who served with Star Trek creator Gene Roddenberry in the Los Angeles Police Department.

The Klingon appearance has evolved over the years, but screenwriter Gene L. Coon's only physical description of them in his "Errand of Mercy" script was "oriental" and "hard-faced".

Worf acknowledged the difference in appearances when the crew of Deep Space 9 returned to the 23rd century in the episode "Trials and Tribble-ations", but offered no explanation, saying merely, "We do not discuss it with outsiders."

Jak'tahla is a phase in a Klingon's maturation roughly analogous to puberty, though according to Jean-Luc Picard that word "hardly does it justice". Its effects include accelerated hair growth, mood swings, increased aggressive tendencies, and odd cravings for the blood of a live kolar beast.

In 2375, due to his exposure to the metaphasic radiation on the Ba'ku planet, Lieutenant Commander Worf acquired a gorch on his nose, even though he was thirty-five years old and well past Jak'tahla.

General Chang quoted Shakespeare throughout Star Trek VI: The Undiscovered Country. In fact, his final line, spoken just before he is obliterated by torpedo fire, is lifted from Hamlet's famous soliloquy: "to be, or not to be..."

Klingons have never been seen to cry. This is due to the fact that they do not possess tear ducts. This does not mean that Klingons don't feel sadness. They simply express their emotions differently.

In the Star Trek: Voyager episode "Lineage", B'Elanna Torres pushes for genetic alterations to her unborn child in order to make her more human, before her human husband convinces her to embrace her Klingon heritage.

Reagan visited the set during the filming of the Star Trek: The Next Generation episode "Redemption", which involved an approaching Klingon civil war. Asked what he thought of the Klingons, Reagan remarked, "I like them, they remind me of Congress."

Worf was permitted to wear a Klingon warrior's sash, sometimes called a baldric, over his regular duty uniform.