Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * MACKEY CATHERINE J	2. Date of Event Requiring Statement (MM/DD/YYYY) 6/30/2021	3. Issuer Name and Ticker or Trading Symbol Trillium Therapeutics Inc. [TRIL]
(Last)        (First)        (Middle) C/O TRILLIUM THERAPEUTICS INC., 2488 DUNWIN DRIVE	4. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director                          _____ 10% Owner _____ Officer (give title below)        _____ Other (specify below)
(Street) MISSISSAUGA, A6 L5L 1J9       (City)              (State)              (Zip)	5. If Amendment, Date Original Filed(MM/DD/YYYY)	6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

Remarks: Exhibit 24 - Power of Attorney

No securities are beneficially owned.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MACKEY CATHERINE J C/O TRILLIUM THERAPEUTICS INC. 2488 DUNWIN DRIVE MISSISSAUGA, A6 L5L 1J9	X

Signatures
/s/ James Parsons, Attorney-in-Fact		7/2/2021
**Signature of Reporting Person		Date