Russell - Combine OverWiki, the original Half-Life wiki and Portal wiki

Portal Storm, Half-Life Wiki

Expiration Date - Official TF2 Wiki

Garden Gnome - Combine OverWiki, the original Half-Life wiki and Portal wiki

Ivan the Space Biker - Combine OverWiki, the original Half-Life wiki and Portal wiki

Combine OverWiki, The Original Half-Life and Portal Wiki, Turns 10 – LambdaGeneration

Odell - Combine OverWiki, the original Half-Life wiki and Portal wiki

Ex Valve dev Matt Wood on the HL and Portal cross over, Valve planned big things back in 2006-7 with HL and Portal, Gabe said in 2007 Chell will have a relation with Half-Life characters : r/HalfLife

Advisor Platform, Half-Life Wiki

Half-Life 2: The Combine Advisor's Psychic Shield (with subtitles for the Combine radio chatter)

Lambda logo - Combine OverWiki, the original Half-Life wiki and Portal wiki

Chell - Combine OverWiki, the original Half-Life wiki and Portal wiki