6-K

SECURITIESAND EXCHANGE COMMISSION

Washington,D.C. 20549

FORM6-K

REPORTOF FOREIGN PRIVATE ISSUER

PURSUANTTO RULE 13a-16 OR 15d-163

UNDERTHE SECURITIES EXCHANGE ACT OF 1934

Forthe month of November 24, 2025

AlterityTherapeutics Limited

(Name of Registrant)

Level 14, 350 Collins Street,Melbourne, Victoria 3000 Australia

(Address of Principal Executive Office)

Indicateby check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F ☒       Form 40-F ☐

ThisForm 6-K is being incorporated by reference into our Registration Statement on Form S-8 (Files No. 333-251073,333-248980 and 333-228671)and our Registration Statements on Form F-3 (Files No. 333-274816,333-251647, 333-231417and 333-250076)

ALTERITYTHERAPEUTICS LIMITED

(adevelopment stage enterprise)

The following exhibits are submitted:

1

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: November 24, 2025

2

Exhibit 99.1

Appendix 3X

Initial Director’s Interest Notice

Rule 3.19A.1

Appendix 3X

Initial Director’s InterestNotice

Information or documents not available now must be givento ASX as soon as available. Information and documents given to ASX become ASX’s property and may be made public.

Introduced 30/9/2001.

We (the entity) give ASX the following information under listing rule 3.19A.1 and as agent for the director for the purposes of section 205G of the Corporations Act.

Part 1 - Director’s relevant interests in securities of which the director is the registered holder

In the case of a trust, this includes interests in thetrust made available by the responsible entity of the trust

Note: In the case of a company, interests which come within paragraph (i) of the definition of “notifiable interest of a director” should be disclosed in this part.

• See chapter 19 for defined terms.

  11/3/2002	Appendix 3X Page 1

Appendix 3X

Initial Director’s Interest Notice

Part 2 – Director’s relevant interests in securities of which the director is not the registered holder

In the case of a trust, this includes interests in thetrust made available by the responsible entity of the trust

Part 3 – Director’s interests in contracts

Note: In the case of a company, interests which come within paragraph (ii) of the definition of “notifiable interest of a director” should be disclosed in this part.

• See chapter 19 for defined terms.

  Appendix 3X Page 2	11/3/2002