🧵 Grammar · Clauses, Connectors & Sentence Style
Defining Relative Clauses
The little clauses that tell your listener exactly who or what you mean — no commas, one extra idea packed straight into the sentence.
Grammar › Clauses, Connectors & Sentence Style › Defining Relative Clauses
The rule in one sentenceA defining relative clause tells us exactly which person or thing we mean, uses who / which / that with no commas, and often drops the pronoun completely when it isn’t the subject — Jessica Chastain is the actress who played Tammy Faye Bakker, but The Eyes of Tammy Faye is the film many critics praised most that year (no pronoun needed at all).
What a defining relative clause actually does
Some sentences need extra information just to make sense. If you say “The actor won an Oscar”, nobody knows which actor. Add a defining relative clause and the sentence suddenly identifies exactly who you mean: “The actor who played Wladyslaw Szpilman won an Oscar.” Without that clause, the sentence is incomplete — that’s what makes it “defining”.
English glues the extra clause straight onto the noun using a relative pronoun: who for people, which for things, and that for either. There are never commas around a defining clause, because commas would suggest the information is “extra” rather than essential — and here it absolutely isn’t optional.
🎬 Compare: “Christian Bale is the actor who played Trevor Reznik in The Machinist” (defining — tells us exactly which actor) vs. simply “Christian Bale, a British actor, starred in The Machinist” (no defining clause needed — we already know who he is).
The clause earns its place in the sentence only when the listener genuinely needs it to identify the noun.
One more trick makes English sentences flow: when the relative pronoun is the object of its own clause, you can often drop it entirely. “The televangelist Jessica Chastain plays in The Eyes of Tammy Faye is Tammy Faye Bakker” works perfectly with no pronoun at all — English speakers do this constantly in everyday conversation.
How to build it
👤 People — subject of the clause
- Huw is the boy who narrates How Green Was My Valley, looking back on his childhood.
- Daniel Day-Lewis is the actor that played Abraham Lincoln.
- Willem Dafoe is the actor who played Van Gogh in At Eternity’s Gate in 2018.
🎬 Things — subject of the clause
- The Sound of Music is a film which broke box-office records in 1965.
- The Exorcist was the film that made cinema audiences afraid of the dark.
- Regina King is the director that won an Emmy for directing Watchmen.
✂️ Object of the clause — pronoun optional
- The performance (that) critics praised most that year was Jessica Chastain’s Tammy Faye Bakker.
- The novel (that) Thomas Keneally wrote inspired Schindler’s List.
- The televangelist Jessica Chastain plays (no pronoun needed at all) is Tammy Faye Bakker.
📍 Places & times
- Cair Paravel is the castle where the Pevensie children rule in The Chronicles of Narnia.
- 1994 was the year when Forrest Gump won Best Picture.
- Vienna is the city where Before Sunrise is set.
When to use which: keep it or drop it
Keep the pronoun — subject clauses
- If the relative pronoun is doing the action itself, it must stay: the boy who narrates How Green Was My Valley — “who” is the one doing the narrating, so it can’t be removed.
- This is true for people, things, places and times alike.
- Test: if removing the pronoun leaves the clause without a subject, it’s staying.
You can drop the pronoun — object clauses
- If the noun the clause describes is the object of the clause’s own verb, the pronoun is optional: the televangelist (who) Jessica Chastain plays — “Jessica Chastain” already has its own subject, so “who” isn’t essential.
- This is extremely common in spoken and written English alike — dropping the pronoun sounds completely natural, not lazy.
- Test: if the clause already has its own subject before the verb, the pronoun can go.
Signal words: the relative pronouns themselves
Unlike tense lessons, the “signal words” here are the grammar itself — each pronoun tells you what kind of noun is being defined.
Visual guide
Teacher Teddy’s illustrated guide to this rule is being drawn — the full swipe-through infographic will appear here soon.
Common mistakes
❌ The actor, who played Trevor Reznik in The Machinist, is Christian Bale.
✅ The actor who played Trevor Reznik in The Machinist is Christian Bale.
Defining clauses never use commas — commas signal “extra, non-essential” information, and here the clause is essential to identify which actor.
❌ The director which made The Exorcist also directed The French Connection.
✅ The director who made The Exorcist also directed The French Connection.
“Which” is for things, not people — William Friedkin needs “who” here.
❌ The director won an Emmy for Watchmen was Regina King.
✅ The director who won an Emmy for Watchmen was Regina King.
A subject relative pronoun can never be dropped — only object pronouns are optional.
❌ The actress who she played Katniss is Jennifer Lawrence.
✅ The actress who played Katniss is Jennifer Lawrence.
Don’t double up: “who” is already the subject of “played” — adding “she” repeats it unnecessarily.
Exceptions & tricky cases
Four things worth knowing once the basic pattern feels comfortable.
1. “That” belongs only to defining clauses. You’ll never see “that” after a comma — non-defining clauses (extra, droppable information) always use who/which instead, and get their own dedicated lesson.
2. “Whose” works here too, for possession. Se7en is the film whose ending shocked cinema audiences in 1995. This page keeps things simple with who/which/that — “whose” and “whom” get a full advanced lesson of their own.
3. Formal English keeps the preposition up front. “The director to whom the award was given” is correct but formal; everyday English prefers “the director who was given the award” or drops the preposition to the end.
4. “Who” vs “that” for people is a style choice, not a strict rule. Both “the actor who played Trevor Reznik” and “the actor that played Trevor Reznik” are correct — many style guides simply prefer “who” for people, so pick one and stay consistent.
Practice: choose the right relative pronoun
Eight quick questions — every one built around a real film, actor or director.
1. Jessica Chastain is the actress ___ played Tammy Faye Bakker.
“Who” is for people — Jessica Chastain is a person.
2. The Exorcist was the film ___ terrified cinema audiences in 1973.
“That” works for things — “who” can never describe a film.
3. The novel ___ Kurt Vonnegut wrote became the film Slaughterhouse-Five in 1972.
A novel is a thing, so “which” (or “that”) is correct — never “who”.
4. Cair Paravel is the castle ___ the Pevensie children rule in The Chronicles of Narnia.
“Where” introduces a defining clause about a place.
5. 1994 was the year ___ Forrest Gump won Best Picture.
“When” introduces a defining clause about a time.
6. Christian Bale is the actor ___ played Trevor Reznik in The Machinist.
“Which” never describes a person — “who” is correct here.
7. Regina King was the director ___ won an Emmy for directing Watchmen.
Regina King is a person, so “who” is the natural choice here.
8. The actor ___ played Detective Carter in Rush Hour is also famous as a stand-up comedian.
“Who” is the subject of “played” here, so it can’t be dropped — only object relative pronouns are optional.
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