diff --git a/Makefile b/Makefile
index 427c5d99b10a57a1e0c501083978fc6627f21553..13b8784a364fdaca972c9f332e464a13949d3cf3 100644
--- a/Makefile
+++ b/Makefile
@@ -24,8 +24,8 @@ all: php-lint php-unit-test php-browser-test mobile static-code-analysis utility
 
 # Image Groups
 ####################
-php-lint: php-lint_5.6 php-lint_7.0 php-lint_7.1 php-lint_7.2 php-lint_7.3 php-lint_7.4 php-lint_8.0 php-lint_8.1 php-lint_8.2 php-lint_latest
-php-unit-test: php-unit-test_5.6 php-unit-test_7.0 php-unit-test_7.1 php-unit-test_7.2 php-unit-test_7.3 php-unit-test_7.4 php-unit-test_8.0 php-unit-test_8.1 php-unit-test_8.2 php-unit-test_latest
+php-lint: php-lint_7.0 php-lint_7.1 php-lint_7.2 php-lint_7.3 php-lint_7.4 php-lint_8.0 php-lint_8.1 php-lint_8.2 php-lint_latest
+php-unit-test: php-unit-test_7.0 php-unit-test_7.1 php-unit-test_7.2 php-unit-test_7.3 php-unit-test_7.4 php-unit-test_8.0 php-unit-test_8.1 php-unit-test_8.2 php-unit-test_latest
 php-browser-test: php-browser-test_8.2 php-browser-test_latest
 mobile: android-build-server
 static-code-analysis: static-code-analysis_latest static-code-analysys_php static-code-analysys_python static-code-analysys_android
@@ -34,9 +34,6 @@ dotnet: dotnet_3.1 dotnet_6.0
 
 # PHP Lint Images
 ####################
-php-lint_5.6: php-lint/5.6/Dockerfile
-	docker build $(BUILD_ARGS) -t ${REPO_ORG}/php-lint:5.6 -f php-lint/5.6/Dockerfile php-lint
-
 php-lint_7.0: php-lint/7.0/Dockerfile
 	docker build $(BUILD_ARGS) -t ${REPO_ORG}/php-lint:7.0 -f php-lint/7.0/Dockerfile php-lint
 
@@ -66,9 +63,6 @@ php-lint_latest: php-lint_8.2
 
 # PHP Unit Test Images
 ####################
-php-unit-test_5.6: php-unit-test/5.6/Dockerfile
-	docker build $(BUILD_ARGS) -t ${REPO_ORG}/php-unit-test:5.6 -f php-unit-test/5.6/Dockerfile php-unit-test
-
 php-unit-test_7.0: php-unit-test/7.0/Dockerfile
 	docker build $(BUILD_ARGS) -t ${REPO_ORG}/php-unit-test:7.0 -f php-unit-test/7.0/Dockerfile php-unit-test
 
diff --git a/php-lint/5.6/Dockerfile b/php-lint/5.6/Dockerfile
deleted file mode 100644
index 26c505d6a933b9e0b813fdf7cd8499670c6e6a70..0000000000000000000000000000000000000000
--- a/php-lint/5.6/Dockerfile
+++ /dev/null
@@ -1,21 +0,0 @@
-FROM php:5.6-alpine
-
-ARG BUILD_DATE
-ARG VCS_REF
-ARG VERSION
-LABEL org.label-schema.build-date=$BUILD_DATE \
-      org.label-schema.name="PHP 5.6 linter" \
-      org.label-schema.description="" \
-      org.label-schema.vcs-ref=$VCS_REF \
-      org.label-schema.vendor="University of Nebraska - Lincoln" \
-      org.label-schema.version=$VERSION \
-      org.label-schema.schema-version="1.0" \
-      maintainer="Alan Nelson <alan.nelson@nebraska.edu>"
-
-RUN apk add --no-cache bash
-
-COPY php-lint docker-entrypoint /usr/local/bin/
-RUN chmod 755 /usr/local/bin/docker-entrypoint /usr/local/bin/php-lint
-
-ENTRYPOINT ["docker-entrypoint"]
-CMD ["--help"]
diff --git a/php-unit-test/5.6/Dockerfile b/php-unit-test/5.6/Dockerfile
deleted file mode 100644
index 2efbdb1d9d7987b5ce25c4590638b08022a425d9..0000000000000000000000000000000000000000
--- a/php-unit-test/5.6/Dockerfile
+++ /dev/null
@@ -1,23 +0,0 @@
-FROM php:5.6-alpine
-
-ARG BUILD_DATE
-ARG VCS_REF
-ARG VERSION
-LABEL org.label-schema.build-date=$BUILD_DATE \
-      org.label-schema.name="PHP 5.6 Unit Tester" \
-      org.label-schema.description="" \
-      org.label-schema.vcs-ref=$VCS_REF \
-      org.label-schema.vendor="University of Nebraska - Lincoln" \
-      org.label-schema.version=$VERSION \
-      org.label-schema.schema-version="1.0" \
-      maintainer="Alan Nelson <alan.nelson@nebraska.edu>"
-
-RUN apk add --no-cache bash nodejs nodejs-npm $PHPIZE_DEPS \
-    && pecl channel-update pecl.php.net \
-    && pecl install xdebug-2.5.0 \
-    && docker-php-ext-enable xdebug \
-    && apk del --no-cache $PHPIZE_DEPS
-RUN curl -o /usr/local/bin/composer https://getcomposer.org/composer.phar \
-  && chmod 755 /usr/local/bin/composer
-
-CMD ["bash"]