Alex Kirby may refer to:

• Alex Kirby (journalist), British journalist
• Alex Kirby (Blue Heelers), a fictional character from Australian TV series Blue Heelers

• 3-Methoxyphenol
• 3-methoxyphenol
• 3-methyl-1,3-dihydroindol-2-one:NADP+ oxidoreductase
• 3-Methyl-19-methyleneandrosta-3,5-dien-17beta-ol
• 3-Methyl-19-methyleneandrosta-3,5-dien-17β-ol
• 3-Methyl-1-butanol
• (3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring))
• 3-Methyl-3-hydroxybutyrate
• 3-Methyl-3-hydroxybutyric acid
• 3-methyl-3-hydroxybutyric acid
• 3-Methylbutanal
• 3-methylbutanal
• 3-methylbutanol:NAD(P)+ oxidoreductase
• 3-methylbutanoyl-CoA:acceptor oxidoreductase
• 3-methylbutanoyl-CoA:electron-transfer flavoprotein oxidoreductase
• 3-methylbutyrate
• 3-methylcrotonoyl-CoA:carbon-dioxide ligase (ADP-forming)
• 3-Methylcrotonylglycinuria
• 3-Methylfuran
• 3-methylglutaconyl-CoA
• 3-Methylhistidine
• 3-methylhistidine
• 3-methyl-L-histidine
• 3-Methyl-L-histidine
• 3-Methylornithine