diff --git a/modules/git/commit_message.go b/modules/git/commit_message.go
index 0729609d87e..9aa3a6966a3 100644
--- a/modules/git/commit_message.go
+++ b/modules/git/commit_message.go
@@ -131,3 +131,17 @@ func (c *Commit) AllParticipantIdentities() []*CommitIdentity {
 	}
 	return c.allParticipants
 }
+
+// CoAuthorIdentities returns the commit's co-authors: the participants without the
+// author and the committer, which are already displayed separately. This avoids
+// surfacing the committer as a "co-author" (see issue #38384).
+func (c *Commit) CoAuthorIdentities() []*CommitIdentity {
+	var ret []*CommitIdentity
+	for _, p := range c.AllParticipantIdentities()[1:] { // index 0 is always the author
+		if c.Committer.Email != "" && strings.EqualFold(p.Email, c.Committer.Email) {
+			continue
+		}
+		ret = append(ret, p)
+	}
+	return ret
+}
diff --git a/modules/git/commit_message_test.go b/modules/git/commit_message_test.go
index 1d13f818033..ba5927d9fd6 100644
--- a/modules/git/commit_message_test.go
+++ b/modules/git/commit_message_test.go
@@ -80,3 +80,42 @@ func TestCommitMessageAllParticipantIdentities(t *testing.T) {
 		assert.Equal(t, c.participant, c.commit.AllParticipantIdentities())
 	}
 }
+
+func TestCommitMessageCoAuthorIdentities(t *testing.T) {
+	sig := func(n, e string) *Signature { return &Signature{Name: n, Email: e} }
+	idt := func(n, e string) *CommitIdentity { return &CommitIdentity{Name: n, Email: e} }
+	cases := []struct {
+		commit    *Commit
+		coAuthors []*CommitIdentity
+	}{
+		{
+			// a genuine co-author (neither author nor committer) is reported
+			&Commit{
+				Author: sig("a", "a@m.com"), Committer: sig("c", "c@m.com"),
+				CommitMessage: CommitMessage{MessageRaw: "Co-authored-by: x <x@m.com>"},
+			},
+			[]*CommitIdentity{idt("x", "x@m.com")},
+		},
+		{
+			// the committer is shown separately as "committed by", so it must
+			// not appear as a co-author even though it is a participant
+			&Commit{
+				Author: sig("a", "a@m.com"), Committer: sig("c", "c@m.com"),
+				CommitMessage: CommitMessage{MessageRaw: "Co-authored-by: c <c@m.com>"},
+			},
+			nil,
+		},
+		{
+			// regression for #38384: a Co-authored-by trailer naming the author
+			// must not cause the committer to be surfaced as the co-author
+			&Commit{
+				Author: sig("silverwind", "me@silverwind.io"), Committer: sig("bircni", "bircni@icloud.com"),
+				CommitMessage: CommitMessage{MessageRaw: "Co-authored-by: silverwind <me@silverwind.io>"},
+			},
+			nil,
+		},
+	}
+	for _, c := range cases {
+		assert.Equal(t, c.coAuthors, c.commit.CoAuthorIdentities())
+	}
+}
diff --git a/routers/web/repo/commit.go b/routers/web/repo/commit.go
index d8953878184..b1b1909e10c 100644
--- a/routers/web/repo/commit.go
+++ b/routers/web/repo/commit.go
@@ -398,7 +398,7 @@ func Diff(ctx *context.Context) {
 	verification := asymkey_service.ParseCommitWithSignature(ctx, commit)
 	ctx.Data["Verification"] = verification
 	ctx.Data["Author"] = user_model.GetUserByGitAuthor(ctx, commit)
-	ctx.Data["CommitOtherParticipants"] = gituser.BuildAvatarStackData(ctx, commit.AllParticipantIdentities(), nil).Participants[1:]
+	ctx.Data["CommitOtherParticipants"] = gituser.BuildAvatarStackData(ctx, commit.CoAuthorIdentities(), nil).Participants
 	ctx.Data["Parents"] = parents
 	ctx.Data["DiffNotAvailable"] = diffShortStat.NumFiles == 0